Thanks for all the replies. Sounds like something of a coin toss, each type with their own set of problems. The last G body I had was a Grand Prix that I swapped from V6 to SBC. I used ebay mid length headers that went on with minor fitment issues. Will probably do that again, at least I've been through it once. Long ago (mid 80s) I had a 78 Cutlass that I put a 350 Olds in and put long tubes on that, seems like it went well but that was a long time ago.
I am shopping for a car right now, have my mind pretty much set on an El Camino. There are several for sale presently and will most likely get one of them. Hope to start out with something built with a small block this time. Exhaust shopping right now might not seem to make sense, but I really do have reasons.