Think about what you are saying. Longer shaft will drop the blade lower. Then the deck height wheel levers will be off. And on a hi-vac deck, the blade might hit the lower rolled in deck lip.I can find the Briggs 163 cc 7.25 torque engines with the 25 mm shaft diameter but none with the 2 3/4 inch shaft length. All of them are 3 and 5/32" now. Will the longer shaft length be ok???