I don't know about fitting a big block in an AD truck, but Bigbolt or 1/2 ton, you will run into the same problems. Seems to be very few folks that have pulled off that swap, and not much if any info on it.
The engine compartment on the small trucks up to about 2 ton is essentially the same, you don't gain any room by using a Bigbolt.

If you use the late model frame and axles/suspension, then the front wheels will be noticeably outside of the front fenders. Pull a tape and see what it looks like. For that reason among others I don't care much for a late model frame swap in an AD truck.

How will you use the truck?
Will the supercharger help or hurt those plans?

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-