I'm going to ask you what you mean by "restore". There is no legal definition. The car shows like "Fast & Loud" are defining it as making the car run under it's own power and shining things up a bit. In the classic car world it means that EVERY nut, bolt, and screw has been removed and EVERY component returned to it's proper, original function. To me, that's what a restoration is. A simple respray is sometimes called a restoration but not in my mind. There is, of course, a lot of room in between.

Anyhow - to give you decent feedback we'll need to know how YOU define it. Either way I wouldn't replace an OM617 with an OM 616. The 617 is underpowered enough as it is in the bigger body and putting less HP in there does no one any favors. 617's are not all that pricey at PnP so I'd go that way. As someone else mentioned, decent 240D bodies are fairly common though you may have to trailer one home - well worth the investment if you really want a 240D. You'll spend MANY times the price of a better body trying to bring back a rusty one.

Dan