727 or 904 tranny

Your slant tranny will not bolt up to a v-8. They have different bell housings. Using a 727 in an early A requires some "massaging" around the pinchweld at the tunnel.(I've never done this only from previous posts) the 904 will drop in pretty easily. On my 63 I went with a floor mounted cable shifter and a bouchilon kick down linkage. I had to cut out and reshape the area where the bouchilon cable and brackets attached because they hit on the floorpan/tunnel area. Also you will need a new driveshaft that will be shorter, also I assume you have a ball and trunnion coupling that should be upgraded to spicer type universal joints.