The Chevy 350 tranny tail is angled down at 3-4 deg when carb is level. there is some room for pinion angle mismatch. I have also made my own. You need to set engine in, meeting all the parameters and see, with a "broom stick", how the drive shaft will be. Or, of course, view a few swaps in person and take many pics and measurements and note the parts used. Once you get the motor mounted on the side mounts and leveled, you will know exactly where the tranny mount needs to be. I think it will be pretty far below frame rails. I know you know all this basic stuff, just mentioning it. You can shim the rear diff somewhat to achieve near equal and opposite pinion/tailshaft angles. Some intake manifolds have different carb surface angles, you can play with that also. Also I'm thinking you have to get the motor down low on AD to get the pinion angle. Not sure. I'm just taking up space until persons who have done it chime in. What did an internet search show? This is a common swap,yes?
