got a factory straight six 3 on the floor gonna rip that out and throw something else in need suggestions

 

It depends if you're starting with scratch, if you have one or the other there you go. A magnum 318 or 360 from a truck would be a good place to start with a 4 speed. A 440 would be my pick for a drag.car 30 years ago but now I'd like to go with a late hemi, there's a lot to pick from.

 

It is only limited by your budget..