First question is why? I raced 39" cars for a year or so and then bought a 41" car and my whole outlook on racing changed. The 41" car is so much easier to drive,set-up,and hook-up on a slick racetrack. I'd never go back.
Your Question: Move the motor, not the suspension. Move the motor from the front of the frame-uprights to the back, inside the cockpit. You'll havbe tyo shave some material off of the motorplate to get it to fit, but you'll be happier in the long run. Next, cut 1.5" off of your driveshaft and go racing. Good luck, you'll have to be pretty quick on the wheel to keep up with the racecar. The 38's and 39s react far quicker than the 40's and 41's.