In the extreme situation the short shaft would.

Don't forget, the longer the hub, the greater the vibration. This problem increases more rapidly than your increase in length. Just a little change in length makes a considerable difference.

You can make your long shaft engine as long as what the crankshaft will aloow you to use it as a prop shaft.

You can cut the long shaft off and thread it and make a hub as long as you could on a short shft engine by threading the hub onto the shaft.

Another point of view is that the long shaft engines are usually close to 3/8" whereas the short shaft engines are 5/16" or 8mm in diameter.

Enjoy,

Jim