Those Crager 390C 15x7 have 3.5" backspace. A factory Mopar 15x7 rim is 4.25" backspace that will fit your brakes and suspension. So the Crager will push you tires out toward the fender lip 3/4"... that's not good. The most narrow 70 series 15" common tire I found was a 195/70/15 (7.7" treadwidth, 25.7" diameter). That's too tall and wide with that rim pushed out 3/4"
With a 15x7 rim with 4.25" backspace you can fit a 215/60/15 tire fairly safely in front. 215/60/15 is 8.5" treadwidth and 25.2" diameter. Some (including myself) have fit 225/60/15 but that is very close and dependent on alignment setting, panel repair, etc.
That Crager is a 2-piece rim. Ask Crager if they can make a 15x7 with 4.25" custom backspace for you for the front trims. Or if you want a fat 70 series tire, ask for 15x6 rim with 4" backspacing and run 195/70/15's
In the back a 15x8 with 4.25" backspacing with factory rear axles (5x4 pattern) tend to allow a the widest tires. Should be able to fit 245,255,265/60/15 at factory ride height with original leaf springs. If rear is higher, you can fit wider.
Or are you running aftermarket 5x4.5 bolt pattern in the rear and front?