Later model 3.8 swap in an "A" body

I did the 3.9 V6 in my 66 dart wagon and it is a lot harder to do then the 5.2 the v6 eng mount in the center of the eng and 5.2 are in the same location as the rest of the v8 motors and with the the overdrives you still have to cut the floor for the o/d and the v6 with 3.23 don't work worth a **** I had to go with the 3.55 and with I got abot 22 mpg and in my 64 Dart with the 5.2 i get 23 to 24 mpg with 3.91 in it and I think both cars weigh about the same both cars had a/c. I did all the wiring my self and if I had to do another one I would do the V8.