68-72 rotors on 73+ spindles?

The issue is that I have sbp wheels on a '68 Barracuda, and I got eager on the disc conversion without doing proper research. I have 14' front wheels and 15' rear wheels, both in sbp. I think I may just end up selling the lbp disc setup and saving up for an SSBC kit. I don't want to buy new wheels and tires just to put brakes on my car.
and too bad you're so far away, I'd be interested in the spindles but shipping from Alaska would be HUGE im sure