advice/opinions re: new engine for 1992 300D

[aeasher]

I'm new to the forum. I have a 1992 300D w/ 193000 miles. The bad news is it broke a timing chain at highspeed. Maybe a vacuum pump failure. It doesn't take much imagination to guess the rest.

I found a fellow who will replace the engine but I have some choices I'd like to get some opinions on.
He does not think the 2.5 tubo was one of their best and I can't find anyone who disagrees.
He suggests I put in one of the following:
1. 2.5 non-turbo w/160,000 miles.
2. 87 3.0 6 cyl. w/120,000 miles.
3. 1995 300D w/ 170,000 miles. This is about a third more in cost than the other two.
All, including install, very reasonably priced. He has done these adaptations before, and I'm confident that the job will be done well.

The question is, what engine to go with.
He believes the 95 m606 is one of their best engines. I've heard they had problems with the glow plugs breaking off in the head.
My mechanic thinks the 2.5 just for ease of install and ordering future parts.
The car is in wonderful condition inside and out. Just replaced the evaporator in May so I had planned to hold onto it awhile.

Any comments and opinions will be welcome.
Thanks