88 300E W124: Worth Keeping?

Hello all,
I have a 88 300E W124 (with the 103 engine). I bought the car brand new in 1988. Right now, it has 240,000 km (150,000 miles) and the body and interior of the car are perfect. However, it's leaking oil like crazy (I think the valve cover gasket is bad) and it probably needs a valve job anyway. Also, the air conditioner doesn't work...evaporator is leaking, receiver/drier is leaking, compressor seal is leaking, and probably some hose is leaking as well.

The MB dealer that gave me the best quote for the fixing the above problems is:

1) Valve job - including valve cover gasket, valve springs etc. $2,000 CDN ~ $1,500 US.

2) A/C repair - replace everything as described above plus conversion to R-134a $3,000 CDN ~ $2,300 US.

Total: $5,000 CDN ~ $3,800 US

The car, as it stands right now, is worth about $8,000 CDN.

So, I would like to get some opinion from this group. Should I keep the car and spend $5,000 CDN fixing it and enjoy it (maybe for another 5 years?) or should I just sell the car as is and get $8,000 CDN cash? I know I can't buy a used car in a condition that's as good as my car for $8,000...

So, What do you think?

Thanks.