I think during that time frame all Mopars used the same diameter shaft and spline count but I'm not 100% sure on that.

As far as swapping to a more modern looking wheel, be careful what you wish for. More modern usually equals smaller in diameter and that's not always a happy ending when mixed with a manual steered straight axle truck.

If the factory wheels are in fact interchangeable, I'd look for a 1st gen Barracuda woodgrain sport wheel with the 3 stainless/chrome spokes. Sharp looking and enough diameter to manhandle the manual box with.

Kevin