Really want to put period correct slotted mags on my 69 Valiant,but all I see are 14 inch (no problem with that) but there aren’t any good size radial tires. Looking for 255/60/14 and 215/70/14.
Anybody have any leads or are they just not made anymore?

Pick your poison

https://www.tirerack.com/tires/sizes/results.jsp?diameter=14

Don't think the 255/60/14's are going to fit on your car.

Maybe use 14" wheels in the front and 15" in the rear so you can get a better tire selection?

This site has a bunch of useful calculators and comparison tools. On the chart, when you click on a size you will get detailed specs for that size including wheel width requirmement and a pretty complete list of who makes tires in that size. I've found it to be very helpful as I try to decide what to go with. In 14" the biggest you'll find new is 245-60 and you get BFG Radial TA. 15" has a much better selection.
https://tiresize.com/chart/

Try www.dbtires if you want redline radials