If you want to build a torque monster, do everything that Alex (Alward25) recommends and... Drop your port timing.
You will loose on the top but you will gain it on the bottom.
And, Alex and I are working on a special set of drum valves to get all that top end back and still keeping the major bottom end improvement from dropping the port timing. Sorry, they are not available yet but we are working on it.. sorta..
Also, get a 38mm Quad vent air striker... more instant throttle response throughout the rpm range, and 1 hp gain to the rear wheel.
I didn't re-read the entire thread but a woods pipe also helps out..
A auto clutch is also a cool woods option...
Of course there is also the big bore option
But pulling stumps and towing tracked vehicles out of mud holes isn't for everyone