That is what my dads plan is...he is putting a 6.1 hemi in a 68 coronet R/T, with an a518 or a500.

The 45rfe is too bulky
The NAG (from the cars) i dont know much about. i know it doesnt have a slip yoke.

I think for an auto a A518 would be the way to go, with any magnum or HEMI conversion.

That is my opinion...