prop question on 3.7

[spareparts]

we ran a 21 pitch mirage on a 176 Stingray bowrider. The 3.7 was a 165 hp with pertronix iginition, K&N Flame arrestor and an 888 Mercruiser 2BBl Rochester carb. Teh prop had been labbed and double cupped, boat ran right at 52. I'd sugest starting with a 17 pitch on your boat, you're probably going to turn it more rpm than we did, you could probably get away with a 19 p Mirage