40 chevy stock springs and shock

Hello all, IM reading lots of messages here about rear leafs, but cant seem to find just what IM looking for. My 40 chev has almost stock suspension. Knee action and leaf, but I changes the rear to a 10 bolt from a Nova doner car. I changes the front end to a MII crossmember and nows time for a better ride on the back end. My question is whats a good doner car to pick for this change over. I know IM going to make and build new mounts, but what should I be looking for at the bone yard for a good fit. Any help would be great!

Maybe this will help some....
http://www.teufert.net/other/rear%20...dimensions.htm

help..can anyone help,ihave a reoccuring problem with my coil over shocks on jag rear end on my 29 A model.Twice now the thread on the left hand shock worked its way loose from top housing regardless of being loctited and having a locknut there as well.Rodders say it shouldnt happen its a fualty shock(twice) and the shock supplier says its the car build fualt.I,m no mechanic having bought my life long dream car 8mths ago no-one seems tohave a long term solution.any advice appreciated,before i end up in a ditch.p.s. the car is of a high qualitiy build or so other rodders say.