So I bought an 8.75" B body housing, axles and perches for $200...

on dusters and 2nd gen backarudas we know it's possible, but can it be done with the more confined wheel wells of a narrow body?
Depends what wheels you are running. I have a 66 B body rear in a 66 Dart wagon and it works fine, but it has bigger wheel wells than a Barracuda.