For that fat fendered Mopar, look into a Dodge Dakota/Durango chassis and running gear. Or if you want to go to the 'other' side, an S10/S15. Ford Rangers use a split beam front end and are LOUSY handling, think swing axle Bug / Corvair.
The fat fendered 40's cars are too narrow for the full size chassis cars of the 60's/70's. You can always shorten or lengthen as needed but VERY difficult to narrow.