32 Active Thunder

Ok so I have xr drives I wanna switch the lowers to bravo 3's if my xr's are 1.50 to 1 what lower ratio would I need in bravo 3?? Also I would consider trading my xr lowers for a set of bravo 3's The drives are on a Sea Ray sunsport 38 I want the bravo3 for better hole shot cruising speed. I'm running 21 rev 4 props on it now what would I need to run on those bravo 3's. Thanks