The cosmetic differences you know about.
The motor is significantly different but bolts to the same bellhousing. Its also bigger than the same year Chevy. The has higher nickel content in the block, which makes it better suited for hot-rodding. Full pressure oil earlier. And I think there are some crank differences, but don't recall any details.
The radiator is mounted further forward to make room for that long motor.
The front crossmember is setup to mount that long motor, and drops down lower where the radiator frame attaches.
There may be others, but those are the ones I think of.
