Prepping an "early" (~1966) 727 for truck use

Use it as it is, was set up good from the factory. Those years hit hard on each gear change. I’ll add, each trans is set up with clutches and springs for the engine it’s hooked to. 383-361 trans will be different than a 440 trans in that aspect. The small block trans is either 318-340 or 360, and also have different pieces. Get a service manual, it will show what to use.