I've rebuilt a few big block 727's in the past, so I have no fear of them. Presently I have an older pushbutton small block 727, and also a later year (71) big block 727 case. How much of the small block internals can I install in the big block case? I'll be using a shift rod valve body of course, but what do I do about stuff like the early rear pump (which I don't want)? Or, I'll put it this way; what can I not use from the older tranny? Or is it even worth it to try this? Thanks!

The PB 727 internal parts that won't work in a '66 or later trans are the valve body, rear support/pump and the output shaft and related parts.

Everything else will work in a '71 case but the wisdom of using those parts is questionable, the PB trans has the 19-spline input shaft which limits the choice of converters; also the early PB planetary and rear clutch retainer aren't as good as the later parts.