Bias Ply to Radial

[ALLFAITH]

I have G60 14's on 14 x 7 wheels pn a stock 69 Ford 428 CJ Cobra Formal Roof.

I want to step up to 15 inch wheels with radials.

Is there a calculator or webiste that will give me approximate tires sizes as I go from bias to radial and bigger sizes,

Thanks,

Brad