Using your deminsions you will have 3" on each side for clearence, Its a little close but should work fine. On my 46 Ford I only have 2 3/4" on each side and my tires completly fill my wheel wells. As to ordering new axles the simple way is to remove the same amount from each side and deduct that amount from the current axle length. This picture should give you an idea of how close mine is.

Roland