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.
Same as me then;
KH discss on the front with 235/60-14 sbps, and 10x2drums on the back with 295/50-15Lbps. Big and littles. Kidney slot alloys.I like that 60s/70s look.
I put those brakes on in 1999 with the silicon brake fluid, and have not had a lick of trouble in all these years and over 125,000 miles.