In all fairness, you asked "are all bellhousings the same"
Rusty gave you the answer.
All I know is, they have to fit the engine
They have to fit the body
They have to fit the transmission
You have to have a flywheel that is compatible with the bell
Such things as early 273s used a very small clutch/ flywheel. You could use a setup like that, but getting a high performance clutch in one of those won't happen
Something out of a truck won't work, I don't know if it'll clear the body, but it likely will be drilled for a "truck" transmission.
What does that leave us with? About 68--76 340/ 360 A bodies, I would guess.