I have a 69 Super Bee decided to move the springs inboard and mini tub it.I have a truck 60 I am going to shorten so I can fit my 285/70/15 tires in the rear.They fit but are way to close for comfort.The car currently has an 8 3/4 so with 3 extra inches on each side how much from a stock D60 do you want to shorten it?I have a 15x10 wheel with 5.5 backspace.

I know the factory 60's are not equal length so how much shorter on each side would you go to utilize the extra 3 in?

Mount the wheels and tires you want to use and position them in the wheel well where you want them to be. Make sure you consider the ride height so as to not have them too far out. Measure between the inside of the wheels at the hub flange and that is the width of rear you need to build. Remember to subtract for brake drums or rotors whichever the case. It's easy to do.