well, that makes up my mind, was going to go with a gen3 m/p 426 hemi in my 66 dart wagon and 65 belveder, ill stay with my first idea, stroker 400s ..512"
also, if you do have a late 727, think about putting an early front servo in, it really helps 2/3 shift as well, and use the 5.0 apply lever, well worth the 25 bones