Jim,
If you want to switch rotation on a bravo just swap the lowers because they are used to running in a clockwise direction or counter clockwise. The upper will be fine because it has not run that much in rev.
If your going to try different prop rotations on a Bravo the safest thing for the drives would be to swap the drives from side to side, and if you like it, then switch the shifter cables.
Reason being(like shifter pointed to) is that your loading your lower shafts and gears in an opposite direction, causing un-needed stress to the parts. As far as the upper gears go, your now loading the opposite gear that never had a load on it so the gear would be ok, but your still spinning the clutch shaft in the opposite direction, also causing stress on that shaft. In early IMCO drives(like I currently run) IMCO used helicut gears with welded floors, and they only weld one gear in each drive(1 top,1 bottom), so switching rotation with just the shifters can cause gear failure.
I have been slowly upgrading my drives, and deal with AAron and Jason at Max Machine Worx. Very smart guys, answer all my questions, and sell good parts. Just my $.02
LE