The best way I have found is to figure what distance the Camaro crossmember sits off the shop floor in a stock Camaro that year ( I slid under a car like my donor and measured from the crossmember center to the floor) and when you are setting the chassis up set the crossmember on blocks so it is at that height and all squared up and then match the truck to the crossmember. I did that on my 51 Merc and came out exactly where I wanted to be on height with no suspension mods to the subframe.
This is one one of my buddies did that is almost too low, the frame rail of the truck is going to end up on the same level as the bottom of the crossmeber rear legs of the Camaro putting the truck super low. Most guys set the trucks frame a bit higher on the subframe than that.
It does show that you want the subframe and truck frame on the same level plane with each other no matter what the height of each is.
I've seen a couple of messed up frames where the builder tried to "build rake or camber" into the frame when he mated one with the other and that doesn't work
One of the best tutorials on doing the swap is the one by Lux Blue on the Hamb.
Read what he writes and says to do an shows and you should be in good shape. It's long winded because of all the comments but he did an excellent job of describing an showing how to do it the right way.
http://www.jalopyjournal.com/forum/t...ne-day.148978/