Mike,
Looking forward to watching your build. My question is: Are you going to more or less copy ever other P38 tank build (the "classic" build) with lots of axles and radius rods, steering rods, shock adsorbers, spindles, headers etc all hanging out in the wind or are you planning to try to integrate these into some sort of aerodynamic apendage that will provide the mimimum amount of aero drag? If you go with the "classic" build you are then almost completely dependent on having the "best" engine to be able to go fast. If you go with the "aero" approach then you have a leg up on the majority of the other cars. Aero is pretty much a free speed "enhancer" and the reduction of frontal area x coefficient of drag is equal to a proportional amount of horse power increase, i.e. 25% less drag is equal to 25% more horse power.
One other thing about the P38 tank, I know that the center line flange is sure a nice way to make the body removable but it is pretty ugly when it comes to being "aero". Again, looking forward to your build.
Rex