I changed directions dramatically...went with a 518 and JW BELL, Hughes balanced converter. The input shaft on the 518 is 24 spline, and so is the Hughes converter.
Need to order a flexplate (I think) kinda confused now. The 440 is a 1966 forged crank, thin harmonic balancer...so assuming this is an internally balanced engine, and now a balanced converter...wondering which flex plate I need? Any help much appreciated...