I'm thinking of doing some engine work to my G for pulling in an improved class with speed limits of 3.5 to 4 mph with the occasional 6 mph pace. I would like to pull anywhere from 6000 lbs. to 7500 lbs. My tractor has stock dimensions right now with 4230 heads. I'm looking for suggestions on how big to bore and stroke it, carb work, manifolds, cam, and which governor to use. I cannot have 800 parts because the rules don't allow them. I have to use my original crankcase. I would like to run rpms in the range of 1600 to 2000 and to be able to compete or wipe the floor up with 800 cube John Deere G's. Any help to get me started in the right direction would be greatly appreciated. Thanks in advance.