Is my rusty 68 Barracuda salvageable?

...and if you can't find an affordable A body width 8 3/4, one of the best kept secrets is to use a 65-67 B body unit. It was literally a drop in for my 73 Duster. They can be had for under $250 complete if you look hard enough.

Second choice would be an M body 8 1/4, which are very plentiful (relatively speaking), and should only require perch relocation.