Thanks for shooting me a PM, I'm happy to contribute to the conversation.
The dimensions I'm going to list below correspond to our FAB9™ worksheet
HERE.
Typically a 66-67 Nova has an inner fender to fender (A) dimension of right about 67". Our #7154 canted 4-bar rear frame can be built as narrow as 34" (B). A-B= 33". 33" divided by 2 gives you 16.5" (H). H is the width of each wheel tub at it's narrowest.
A 345 tire from sidewall to sidewall when mounted on the wheel is probably just shy of 14" (D) which is an easy number so let's use that.
So if each tub is 16.5" then that leaves you 2.5" per tub for clearance. I would put 1" on the inside (G) and 1.5" on the outside (I) and call it good. More room on the outside makes it
slightly easier to get the wheels off.
So there ya go!
Please note, all of these numbers are off the top of my head. Always measure your vehicle to ensure correct dimensions.