23 Fish Nautique Outboard Conversion

The 71c is probably fine with a few more cubes, though if you had access to a 72c that wouldn’t be a terrible consideration. You wouldn’t be running s large enough prop for the 1” shaft to be an issue, at 1-1/8” the choice are less well known (at least in RH) but they are likely to exist. I don’t think you will get to a 13x14 in that hull unless you build a 383 that only wants to spin 4K rpm. It’s more likely that the stroker small block would allow you to go up to a 13x12, probably spinning it 5000-5500 considering your power goals. 50 would still be a longshot, It takes 20-30hp to add 1mph of speed on the smaller boats, your return is going to be smaller on a 23’. I’d be looking at 450-550hp Big blocks (potentially stroker Big blocks) if 50+ was the ultimate goal. You could spin one slower, too.

Very cool. 50mph is just something to strive for. I'm also aware that too much speed can be dangerous in a hull of that shape so 45 would still make me happy. BBC isn't really on my radar at this point and if the 71c will handle a 383 I'd prefer to go that route.    A higher rpm with a 13X12 is what i keep coming back to anyway. Again, thank you all for the feedback.