65 Valiant Ball and Trunnion Question

The rebuild kits are tough to find, but these guys still list them:
"Detroit"-style ball & trunion repair kit for the front and cross-type universal joint for the rear of all 1960-65 Plymouth Valiant; all 1964-65 Barracuda; all 1961-62 Dodge Lancer and all 1963-65 Dodge Dart (moparmall.com)
The trouble is that the housing becomes worn after all these years, and new ones are unobtanium. The workaround is to have a plate made to fit between the transmission flange and the trunion housing, spacing the housing back so the balls ride in an unworn (or at least less worn) section of the housing. Doesn't take much, maybe 3/16 give or take?
If it's too far gone, probably your only other option would be a driveshaft conversion, as outlined here:
Early Valiant Barracuda Club - ball and trunion U-joint conversion (earlycuda.org)