71 Duster rear tires selection

Don't know the backspace... will measure when I get a chance.
The springs are relocated as described in my first post.

Already got M&H 275/60 15s and they seem great and fit perfectly. The only thing that surprised me was the ammount of thread... I expected same ammount of rubber as on radials and was surprised to see around 1/8"... and seem very soft. No previous experience at all with tires like this...

Now I'm thinking to get more street oriented wheels as a second setup with 295/50/15 BFG in the rear and 215/65/15 BFG in the front...
Two ideas come to mind, either torque thrusts or cop car wheels painted black or white with dog dish hub cups...