The only thing an sm465 fits is an sm465.

I'd take the GM adapter off and use dodge parts IMO. The dodge NV4500 has a bigger input and out put shaft as well as a bigger bell housing.

You will then get the chance at a nv5600.

If you must go GM then go automatic with a standalone 4l80 or Allison using a controller like what Leroydiesel sells.

 

The 47RH is not electronic. 94-95 I think are the years (and you need the 94+ cummins flywheel housing). It has a real tall OD (0.69) too. Huge aftermarket for these trans... probably get a hardened billet everything now.

This thread talks about adding some pressure and toggle switches to have manual control.
Full Manual 47RH - Dodge Cummins Diesel Forum



All that said.... I'm a manual trans guy. In your situation I'd be looking for a parts truck in order to get a 5spd (or 6spd).
edit: or find a 3.07 diff