727 or 904 in a Early A body

You need to decide what method you will use to shift the trans.

the stock 65 set up took a floor mounted shifter and used cables to actuate the trans, not linkages. It was a one year only thing and the cables are getting harder to come by and the place that used to make them seems to be not doing that anymore.

You may want to get a linkage actuated trans and steering column or console set up.

There is also a converter snout difference. Stock early A's had the smaller one. I can't remember which year they went to the larger diameter, but I think 66 was the last year for the small diameter snout, and 67 was the first year. Someone correct me if I'm wrong on that...

Decide which way you want to go, then find the proper parts to get it set up...