Does anyone know of a radial tire That I could put on my 68 coupe deville ? I am just starting to get it back on the road and from what I understand it rides and handles better with Bias Ply tires.

I would opine that it will ride and handle better with radials: that was two of the reasons used in the 60's hype changeover to radials. Use the tire comparison tables in www.tirerack.com to convert the old bias numbers
(X.XX - XX) to radial sizes (XXX/XX/XX)