For an airplane like a Great Lakes, weight is the enemy. The wings were designed to fly well with their original max gross and adding weight to the airframe will just make those wings fly worse. Horsepower will produce climb, but in cruise you will be flying at a higher angle of attack and burning more fuel than the same engine installation on an airframe that is a better match to the operating weight. And the glide will be even closer to what a falling anvil does.

With higher weight, the stall speed and landing speed will go up. The airframe load "G" limits will be lower. So you may not be able to do the maneuvers that you want and you might not enjoy the new handling characteristics at all.

On an 1800lb airplane, adding 100 lbs is 5.5%. In airplanes, that's a lot.

The best advice might be to track down one of the radial installations and try to get to fly in it. Hate to see someone spend 4000 hours on a project and not be happy with the finished result.

Best of luck,

Wes
N78PS