Can you change the prop shaft in a standard bravo to a 1.25 without changing much else?

yes imco has them

The bearing carrier also needs to be changed to accomodate the larger shaft. The splines on the gear end of the Imco will fit the B1 gears. If you use the Merc XR 1.25" shaft it wont fit the B1 gear and you need to go to the XR lower gear set.

Thanks for the help

Give John P at the Bravo Shop a call, he can help you out.

+1.... John did the ones on my BT this spring when he went thru them.