Have you looked at PG Classic? Pretty sure you'll find em there. I don't think theyre DOT approved I bought a set for my 69 A12 roadrunner, they DO appear to be an EXACT copy of the old 69 belts Ive got. Actually PERFECT. Ive seen a lot of arguement over "What if a crash" blah blah... In my opinion? The way these cars are built? If there's a wreck when I'M driving? The dash or steering wheel will be the worst thing. Or God forbid a tree into a door. Also VANS Automotive sells almost all of the BOLTS, hardware, end covers etc needed. I found "Spacers" & washers at a Home Depot. It'll be a good $500-$600 job, but? They Look WAY BETTER than the ratty 53 yr old belts, and I'll have a disclaimer to sign before anyone "Gets In".
Hope this helps a bit!