i purchased a 99 boss 302 in pieces , well it is all together and all new motor twin 454 mpi . my issue is that the guy shorted me one prop so he gave me another prop that is the same as the one that came with the boat. both are mirage plus 23p right hand props. so i went to the local boat mechanic here and he said to run both right hand props instead of a left and a right... he said to just reverse the cable at the controller . i guess my question is a=has anyone done this? are there performance losses from one side getting dirty water from not being a left hand? handling issues? any advise or thoughts ? thanks in advance

People have done this before and have done fine with it. However you could experience listing to one side or the other. Also when re-entry after launching the boat erratic transom movement can occur and obviously ill handling dangers can result. You can always try it and then adjust it back again.
I'd just get a opposite rotation prop and keep the other as a back up.

Brett