V8 W/Powerglide changeover

[Jurassic-1]

I need info. We are restoring a 1964 C10 Fleetside Short bed from a 6 cly. 3 speed to automatic. We changed the motor stands and removed the crossmember for the bell housing. We purchased a factory automatic crossmember and where it mounts has 1 set of holes. (most have 2-3 options) when it is in those holes it is about 4" too far back but the E-brake cables fit but moved forward we need a new set of cables and will need to drill holes to line up. We are trying to build this as close to factory so I am asking anyone who has done this for help. and or photos of a factory v8 automatic underside . The engine is out of a 1965 Impala Wagon.Any help would be appreciated. Thanks