[tlorber]

Thanks guys.
50ish, I haven't had any major issues yet. I bought some motor mounts that adapted the LM7 block to the existing mount holes. Most of the critical measuring is where you locate your cab. There are quite a few threads here that address that.

One thing to consider though--I started out with a 3/4 ton truck, which was had very stiff springs, 9 lug wheels and was long (3/4 tons have a longer box). If I had started with a 1/2 ton , I might have tried to just work with the existing frame. I've heard from a couple people now that you can take front and rear Crown Victoria Suspensions and drop 1/2 ton frames straight onto them. That gives you the same front disk ifs/rear drum setup as an S body. It means you would need Ford wheels, but that's not a huge deal. Again, I have not verified this for myself, but I've heard it on more than one occasion. If true, it would be a lot less work than a frame swap.