63whoopie,
I can't help on a new rear end, but will say I think the Mr. Gasket shifter sounds like a cool deal.
The price is reasonable, and when properly adjusted, your shifting woes would be over.
There is a specific procedure to line the linkage up for proper operation...it isn't real hard to do. It would apply to your column setup as well as to any conversion kit you put in.
I will bet Mr. Gasket has a great set of instructions with the kit. I wonder if there is a Mrs. Gasket
Stuart.