Based on recommendations and observations, I went to Steve at Katy Transmissions and asked him to acquire and build a drag racing TH350 that would have a manual only valve body, a shift kit and a 9" long tailshaft so I could retain my stock driveshaft intact. In otherwords, I wouldn't have to shorten nor lengthen my driveshaft and I wouldn't have to change my drive shaft yokes.
I paid Steve $650 outright for the above described transmission. No core charge, no trade in. Compare that to a typical 'stock' rebuild fee of about $1,400 plus.
This picture shows the 9" tailshaft on the tranny