If the transmission is an SM420, you can very easily convert it to use with an open driveshaft. It only requires that the rear bearing retainer and the yoke be swapped. Those parts come up fairly regularly on everyone's favorite auction site.

-Tim
'51 Chevy 3104 w/'56 235, 848 Head, HEI Dizzy, Corvette Cam, Split Manifold and Dual Carter YF's