I have a new, old stock, Billboards also, but they have a bad reputation for throwing rocks and damaging the paint. And their a bias-ply, not a radial.
I've also thought about the AVONS, then grinding down the letters to glue down the Rubber letters reading Good Year. A lot of people are doing that today.
Roger Kraus is where I got mine from a Group Buy I created here years ago.
https://rogerkrausracing.com/race-tire-pricing/