Reconsidering the Rebuild: Is a Used Engine a Better Solution?

After consulting with several rebuilders, I am reconsidering the practicability of rebuilding this engine.  Depending how much work it needs (valves, seal, guides, rings, cylinder sleeves, pistons, gasket set, etc, not to mention possibly reboring and honing the cylinders...) estimates run from $1500 to $3000 and up.  How practical is that for a car whose value is mostly sentimental rather than financial.  After all, this is NOT a Gull Wing Mercedes!  It is a great driving, classic-style car, that is loyally loved and appreciated by the W115 aficionados.  Both of us.  It is not as if it is about to win the Concours D'Elegance at Pebble Beach.

So the question becomes how much is it worth to me to get it into good running condition.  Let us not forget that in addtion to all the mechanical work required here, it will also need some prep and a paint job, as well as some "freshening' of the interior.  Although I haven't really set a budget for this project, it is clear that costs could easily get out of hand here if I am not careful.... and practical.  So I need to consider if I have any alternatives to rebuilding the engine. 

After doing a few searches on craigs list, some possibilities have arisen.  Several people are selling used, low mileage engines for the 300D at the present time, spread a bit over southern New England and New York.  These are all 300D engines from the later series W123, however.  Prices range from $350-1200.  Some adaptability questions arise, obviously:  will this engine fit;  what are the differences between my engine and these later models, etc.  Is it the same glow plug/ignition system, or are these the later versions?  The basic engine is the same (some may be 2998cc vs mine which is 3005cc), and I think that as long as it is a non-turbo engine, it should be pretty close.  Even the turbo version should work,actually, but I don't want to go that route.

So I am presently pursuing those leads for used engines, and I have been in contact with three sellers, so far.  I still need to evaluate which, if any may work best, and which is the best deal, all things considered.  Two are some distance away, one is still in the car, and one can be delivered to my house.   If it is a decent engine at the right price, this is really a no-brainer.  I can do the installation in my garage... a quick and dirty solution, and relatively cheap.

Stay tuned.