Well, considering that the kit is in 1/25th, I would suggest the rear tires from a modern top fuel dragster or the wide MPC slicks from the early 70's that can be found in numerous drag and show cars.
The rims are actually pretty accurate for the period. As for the engine, you can swap out any 1/25 scale hemi and dress it up with the kit supplied parts. The HEMI in these kits is a bit too narrow.