[Moltensurf]

hi everyone, my name is jonathan, I am the owner of a 1977 i36. I have a small problem, I let my zinc on the prop shaft go bad; now I am needing to buy a new prop. there is not a lot of info online about the subject. I have an atomic 4 gas engine with a 2:1 reduction gear.
I talked to the guys at indigo and they suggest a 12" prop with 12 degree pitch. that is on a three blade prop. I found a 2 blade prop online 12/10 but I was told this is not a good match for my boat, and and that I need something more like a 15", but i'm not sure there is enough clearance between my hull and the prop. is there anyone out there with some info that could be of help?