Long tailshaft 727?

It is longer than your 904 was by about 3" so yes the driveshaft will need to be shorter and the output yoke is bigger on a 727. In other words you'll need a driveshaft/yoke assy. from a Duster (or another A-body with the same wheel base as a duster) with a 727. The long tail shaft 727 is the standard car and light duty truck style. The only short tail shaft versions are the ones used on 4x4's, HD trucks, and motor homes.