One big difference between the two is that the radials will tolerate a wider range of alignment specs. This means you can put a more modern spec alignment on them, which will tend to improve the driving experience by creating a car the handles better and feels smoother to drive. If your normal driver is newer, using radials on the classic with the new alignment specs will make the road feel between the two eras of cars feel closer rather than further apart.

It is not uncommon to see members post on here about how they love their muscle car, but the driving experience is less than stellar compared to their modern econo-box and its no fun anymore and they suddenly feel they need to drop major coin on a coil over system to make it feel "modern."

So, I vote radials with a new alignment. Get 4-5* positive caster, 0-1* negative camber, .125" of total toe in. This with radials will make it feel like a much newer car.

Anyone remember the Pontiac Radial Tuned Suspension system of the mid '70s? The components weren't much different for the early '70s, they did have bigger sway bars, but the alignment specs were significantly different.

That isn't to say its all hellfire and damnation if you chose bias plys. Just stick with the factory recommended suspension alignment and be prepared for a significantly different driving feel compared to your commuter. They do hunt grooves a bit more, flat spot easier, and take a while to warm up and smooth out on cooler mornings. They also will "broadcast" their grip level much more clearly if you are pushing the traction limits and you may be able to recover traction faster when you do exceed their grip.