If its a sterndrive, chances are its not reverse rotation, especially since you said its a bravo. Bravos can turn either direction, so the reverse rotation is simply a shift cable direction change. There are several reputable sources on the topic (none of which I have bookmarked on this computer) but I did have this one:
Its HIGHLY unlikely for that engine to be reverse rotation. The whole point of the later generation outdrives was so they didn't have to make reverse engines, but like was said, change the cam and the distributor gear and you're moving the in the right way.
PS... I forgot to mention... if it was ever a saltwater block (meaning that salt water was used to circulate in the jackets) you cannot use antifreeze in it. Ethylene glycol and salt don't mix, and no matter how much you flush it the pores will always retain some salt.