Ford 9" in 1965 Barracuda...an option?

If your trying to keep it original down to the SBP cragars w redlines, then I would look for an 8.75 mopar SBP axle and bolt it in. If you go for the ford 9", redrill the axles, and drums for your 5 bolt 4" circle and put 7/16" lug studs in it.