1956 chevy stepside short bed frame ?

[justin5976]

I'm an owner of a 1956 chevy short bed stepside and starting on building a resto mod and starting on a frame up rebuild. I am starting on the frame which has the frontend swapped with what looks like a 70-79 Camaro subframe. I have a few questions? I'm looking to do this project right and not cut any corners. It appears the graft of the sub frame was done right but other areas are not to my standards.
First off the motor mounts were moved and welded on and moved an inch beyond the mounting surface (which I believe was for clearance of the SBC distributor from the firewall) problem is the engine sat so low doesn't seem there is any clearance to add headers and power steering pulley almost hitting the power steering box. I bought some metal tower mounts to weld in. Anyone have suggestions?
Second, I'm looking to add a posi rear end with rear disc brakes so purchased 95 impala ss rearend with I believe has a longer wheel base then original. Will this 1.5 inch longer on each side cause me headaches in the future. Again any suggestions would be appreciated.

And my third question is if I use the impala rear and have the Camaro frontend I will have two different bolt patterns for my wheels what is the best way to fix this problem?

I'm new to this forum and to the build world but would like to do as much as I can myself. I want to end up with a old looking truck with some modern updates that will be a nice hiway runner