I have never done a large-scale project like that and would think you would be likely to acquire a bunch of crap and some gems. I did a 50% split with someone who had restored his 113 and wanted to get rid of his extra parts and his replaced parts. That worked well, but we are talking about maybe 15 items including a grill surround and a few other special parts. My other datapoint is I went to an upholstery shop that has been retired and the owner worked on Mercedes from the 60s - 80s. I bought a bunch of stuff (3 hardtops, several mis-matched seat skins, a box of misc including some NOS 108 door caps...). I may have bought a bunch of boat anchors and it WAS a lot of work just to move the stuff. At the same time, I had the opportunity to buy a huge amount of seat skins for cars I don't deal with, mostly 116 and 107. I decided not to take it on. Buy what you know. Otherwise you could end up wasting a huge amount of time. If you know what the parts are and what they are worth, go for it. If you aren't sure, chances are that you could be taking on a mess. If you have the time, fine. If you have the chance to reverse the deal and say "this isn't working for me, I want out" that works too.