1974 Duster 340 Engine and 727 Transmission Questions!!!

A lot of those parts are also a one time purchase. There have been plenty of people on this site that have built 904's that get punished.
Bolt in sprag for a 904... why??? unnecessary. This isn't a 727 that can grenade at an RPM guys run a SB around here. Nobody is likely running a SB here that can get the 904 drum to critical mass levels.

Even the 904 24 spring kit has a less expensive alternative with the reverse wound spring now available.

If he wants to build the 727's, have at it. Swap the long pieces into the other case and be done. A decent 727 kit is under 150 from Northern Auto IIRC.

Pick your parts, pay your money