Great idea! This was always a problem with the 22, the motor was so far away from the driveshafts in mid configuration! Good to hear you're making this, bet it will make a huge difference in how the car drives. 8mm taller is NO problem in my opinion, after all you've got heavy big bore shocks on all corners, adding 8mm onto the central positioned gearbox won't make that much difference in comparison.
Good work