Horsepower, torque, engine size

In VA, a moped must be under 50cc &\or under 5hp, &\or have bicycle pedals. So what I'm looking for, is an 80cc 4stroke 4hp motor. What I can't figure out, is what to look for in hp to torque ratios,or how much torque I'm going to need if I want to be able to go up hills. I'd assume a heavier flywheel mounted on the magneto would help, but I don't know which that would effect. I don't know where to begin.