Almost every fast leaf spring racer uses Caltracs, you should be good to go there, especially if you have stiffly valved adjustable shocks in the rear.

I wouldn’t sweat 20 mm of tire at all, guys are running mid 4’s in the 8th on a 235 drag radial, but it takes lots of work with the tune and suspension at that level.

I would expect yours is going to need at least some power management on the starting line though- between the trans, the explosive power delivery of a supercharger, and I assume a tighter converter than a normal street strip 727. On a radial prepped track it will be ok but on a normal t&t night it might be a struggle.