A light small block A body will be OK with the 23 spline box twocents

Like Cab said it probably has a 3.09 first gear so 3.23 or 3.55 rear gears would be a nice cruiser with some goo mechanical advantage down low. This ramps up the fun factor and the clutch disc will also thank you for it drive

Gus beer

64 Plymouth Savoy
493 Indy EZ's by Nick at Compu-Flow
5-Speed Richmond faceplate Liberty box
Dana 60