1974 Duster 340 Engine and 727 Transmission Questions!!!

I would stay with the 904. Its lighter & draws less parasitic power than the 727. If built with quality parts with attention to tolerances, it will handle anything a 340 can throw at it. Plus you wont have to change the drive shaft.
Thanks for the info. Based on all the replies. looks like the 904 is the way to go... Alec!