rear end choices?

One option is a Lincoln Versailles/ Monarch/ Granada, don't know about "all" Grandadas but some of the Monarchs and the Versailles came with a Ferd 9" and it will bolt in with NO modifications except maybe wedge shims to change the pinion angle. The Versailles had factory rear disks, but finding parts for em is a little iffy.

The axle is a LITTLE wider, can be taken car of with wheel offset. The Ferd perches are I think 1/4" per side wider, bolts right in there.

Precision, others, makes a Mopar -- Ferd conversion U joint.