When I bought my 1969 Barracuda back in the fall of 1968, it came with Firestone Wide Oval bias ply tires. After only a few years, in 1970, that original set of tires was replaced with, again, new Firestone Wide ovals. But the 3rd set of tires I bought were radials. I vividly recall being totally shocked at how much better the radials were and that it was such a big and obvious improvement.

Since 1.2 percent of new cars were delivered with radials in 1970, I'm gonna say radials are just fine for original restoration muscle cars.

**quote from NY Times archives 8/27/81:

All new United States-built cars will have radial tires as standard equipment for the first time in the 1982 model year, the Goodyear Tire and Rubber Company said today.

''This is the first time since the 1968 model year that one tire construction has been standard equipment for all U.S. auto companies,'' said Scott H. Buzby, president of Goodyear Tire.

Through 1968 models, the only tire construction used on new cars was bias ply, and bias-belted construction began to appear on 1969 models, the company said.

By 1970, 86 percent of new cars came with bias-belted tires, and radials accounted for only 1.2 percent of the original equipment market.

The big shift to radial tires began in 1974, when American car makers began making suspensions specially designed for the longwearing, gas-saving radials. Goodyear said the percentage of new cars having radial tires as original equipment jumped from 19.2 percent in 1973 to 43.9 percent in 1974.

For 1982, the only bias-ply tires in new cars will be for temporary-use spares, Goodyear said.

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