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.
You could also do adapters...