Goucho, I don't have my diamond back book handy but they have a website. The also ahve a tall skinny radial that's about 27 or 28 inches tall and has about 4-5 inch tread wisth. Looks like a bias ply. That's what I plan on running on the coupe I'm working on along with thier radial cheaters.
Traditional or not...if there had been radials back in the 40's thru 60's, they would have been running them. I've had old pickups with solid axles (53-56 Fords) that drove like **** and after switching to a set of radials, they straightened right up.
you could always try the ****er excelsior, they look like bias ply but are radials and you can get them in any size.