Here is the deal if a rear end swap is done.

1. I had the current 8.25 narrowed by 2.25” on each side in order to tuck the 12” tires under it, maintain the offset and get a deep dish on the design side of the wheel. So most likely I am looking at a custom width on any size housing.
2. With the 5 speed trans the rear gear needs to go to a 3.91. This will help the 5.9 rev quicker to its power band.
3. As stated in a reply the drums need to go and discs brought in.
4. The assembly would need to be reliable up to 450 hp when I eventually get it there. Hard street driving and an occasional pass or two on the strip or auto cross. No need for it to have to hold full on racing power.

Now the question would be:
With me having very limited experience in working with assemblies and diffs, do I just let someone build this thing from the chunk to the brakes, gather up the parts and build it up myself or do something in between. I don’t have unlimited financial resources but I don’t like cheap junk either.

The biggest concern for me doing this myself is narrowing the housing correctly.