Not sure of the actual wheel base, but I am currently building the 55 Sportsman car using the chassis, and roll cage, etc, but, while using a Monogram 55 Bel Air hardtop 2 in 1 kit body. I had to lengthen the floor approx. a 1/2 inch, with .030 Evergreen sheet styrene, and stretch the tube chassis in the front, to fit the engine, and make the wheel tubs more centered. Only minor problem I am encountering, is, the radiator is close to the front of the engine, needing a smaller single belt, instead of the two belts.
I wanted to do this Pro Street car to look like a passenger 55, as compared to the Pro Mod 55, so the tires would tuck nicely under the stock rear quarters. Might even fit better for the car you want to build. Hope I was able to helps you a bit.