Easiest install for a SB OD, auto trans.

Anything is possible with enough work.
What a clean looking Gremmie.. Used to ride to school with a buddy that had a new 72 3 speed manual.
Always liked them. They made 'um with V8's too.
A 904 with a Gearvendor's OD may fit nice with the 318 between the fenders.
Or a A500 if you could find one.The biggest problem is reworking the trans crossmember to fit with the factory OD. Did a 72 B Body with a A518 years ago. lots of cutting and fitting.