What engine would be the best for performance mods? Buying a new (to me) diesel

[bigjoe25]

LONG POST! You have been warned!

Okay here we go, I got bit by the diesel bug recently and I'm looking for a comfortable cruiser, reliable, good MPG, and somewhat quick (I consider 14.0 and under in the 1/4 mile quick enough)

After doing research I'm finding these old benz can fit all the criteria. I also MUST have an automatic, and for everyone telling me to buy a newer VW, I hear their automatic trans in the diesel cars are junk. It's going to be tough as there are no true bolt on performance parts like the VW's and most things will have to be custom or shipped to Europe to be modded but that doesn't scare me.

For my automotive background I've done some nifty things before. For example, I built a 92 eagle talon up to 600+hp to all four wheels, ran 10.8@130 in the 1/4 mile, no nitrous, full interior, street tires, stock suspension. Got kicked off the track due to not having a roll cage. I've also done some other things such drop a chevy 350 into an old Rx7, supercharged a 86 944 N/A, and built a twin-engined dodge shadow AWD.

So here we go! I have four cars around me to chose from, and I've done research but I'm still undecided. Strangely they all have white exterior color except for one. I'm going to list the cars I'm looking at, and in your opinion which one should I get baring the , mileage, exterior/interior condition, and driving condition is all the same. These cars are all within a 5 minute to 2 hour drive away.

1985 300CD coupe. Price: 2500 cash, dealer. No payment options. 5 minute drive away
Pros:
Complete car-fax history report with tons of maintenance records. Cylinder head with all gaskets and timing chain stuff done in 2012.
Cool looking B-pillarless coupe with all the windows down and sunroof open
OM617 is dead solid reliable
Only car with cloth interior, which is actually a plus in my book.
Did I mention it's freakin' cool looking, timeless classic.
Cons:
2nd slowest of the 4 cars.
Not as much performance options as the other engines
W123 chassis is dated, hard to do suspension mods and find aftermarket wheels. Best I can find is the CLK320 lightweight wheels, and they're only 205 wide. Fine for cruising and light weight for MPG, bad for any serious handling.
Costs the most by a good $700-$1000 premium over the other private owner cars and it's cash only. It's at a dealership so this could explain it.
Has been repainted, the front part of the car looks shiny while the rear looks semi-dull. It's a 10 footer car for paint. Car fax is clean though, I was thinking it was in a fender bender but I guess not.
I'm a 6'5" 265lbs man. I hear the coupes have the worst headroom out of all the cars I've listed, and the backseat is worthless.
I haven't driven this car yet, I've only seen it on the dealership lot despite only being a 5 minute drive away. I just recently found it today.


1986 300 SDL Price: 1500 cash, private dealer.
Pros:
It's a bigger car so I can stretch out on long distance drives.
It's a long chassis, so people can fit in the back easy even with my seat all the way back.
OM603 is arguably the best for performance mods.
I've seen and driven this car in person and it runs great.
It's the cheapest car and I bet he would come down lower as he just bought a new truck and has no need for this car.
Cons:
It's a BIG car. It's a pro and con, nice for the highway, crappy for the city and parking.
Being so big and heavy, it's the slowest car on the list by despite having the most power.
It needs TLC. Runs fine, stops fine, but interior and exterior need work. Little bit of surface rust on the front bumper area, unsure about the under body. Seats are 7/10 which is good, but headliner is trashed, and has cracks in the dash.
Needs a front ball joint/suspension work, and in my experience this can be expensive to replace. Not to mention, I am unsure if it has traditional rear suspension or the self-leveling type. I want to avoid the self-leveling type!
Again on the suspension there is little to no aftermarket, 20+ hour job to replace sway bars, and even though there ARE good aftermarket wheels, they're EXPENSIVE (think $1,000 per wheel not including tires)
It would be much less of a sporty car which is what I'm shooting for.
I am worried about the #14 cylinder heads. Unsure what ones are on it.
Worried some more because it may be a money pit, that's why the initial purchase price is so low.

1993 300d 2.5 turbo. Price: 1700, private owner. is her best offer so far so price = $1701+
Pros:
Interior and exterior is mint, or so it LOOKS like and the guy says
Has receipts for all maintenance dating back to 1999
Suspension wise, has the most aftermarket to make it a great handling sporty car. Also being a newer car, can find some sweet AMG wheels that fit on it.
This is the lightest car, despise being a sedan vs the W123 coupe.
The 2.5 turbo sounds like a good engine. There are mods to work with it, but not as much power compared to the OM603 stock for stock.
Best MPG out of the three.
It's REALLY not that expensive, especially if i can get it under 2000. I'm talking less than 1/2 blue book value.
Cons:
I haven't seen or driven it in person. It's a good 2 and a half hour drive away. I am afraid it could be a total lemon.
I haven't researched the 2.5 turbo a lot. I am unsure of it's reliability compared to the other two engines.
Being the big and tall guy I am, it's really a 3-seater car. My front seat would have to be all the way back and there isn't going to be anyone sitting behind me.


THERE IS ANOTHER OPTION which I may shoot for! There is 1987 300D turbo near me, about a 45 minute drive away. This is my ideal platform for performance! It's at a dealership and....they seem to know what they got. The list price is......5,500! The thing is though they finance. $500 down and I could get away with as low as $150 bucks a month. The thing is, if I were to finance I would rather have a w211 car, but there are no CDI's around me at dealerships within 5 hour drives. I also don't want a W210 because I hear bad things about the electronics and rust issues.