Well David, after doing a lot of measuring and calculating I'm going to go with what I have.
At the very most it might be short 2 MM on the wheelbase. from the firewall to the front wheels, it's slightly longer than my 1/18th scale build. I'm trying to use the sprint car tires, so all my mounting points don't need changed. The right rear sprint car tire is about 3 MM larger than a Big Donkey tire. The left rear is smaller than Big Donkey tires. The right rear sprint car tire is a little wide for this time period, but this car was radical.
On the number 6 build I did a while back, I had to make all new mounts for the front and rear axles. I mounted them solid with metal brackets in the middle of the axles, out of sight. So when I get further along with the build we'll see how it turns out. I do know that too long is usually better than too short. To change it I would need to build a new frame.
Bob