As I understand it, you can get the torque increase from a reduction by simply multiplying the torque by the reduction ratio is that correct?
My engine produces 98hp @ 6750rpm, but maximum torque 231ft/lbs @ 6000rpm. My reduction I've designed is 2.85 which will spin the prop at 2368 & 2105rpm respectively @ 658ft/lbs. A little slow at these rpm, but I designed the unit off a max rpm of 7000 or 2456@prop. I hope to be able to find a wider blade so the overall set-up is quieter. When I go to a prop do I quote them the 658ft/lbs and 2105rpm?