I have a VC. You state yours has a y69 engine while the original engine was a F124 engine.
I have a VC that was originally a F124 and I have bored it out to 162 + .o3o" to give 166 Cu.In. I have not made any other changes to it. It dyno's at 30 horsepower. Pulls strong on 12.4x32 tires, but is a little bit light and spins out without working the engine. I have 1 set of weights to put on it before next year.
The engine has plenty compression and a little work on the cam and opening up the valves to breathe better could probably result in horsepower in the upper 30 range. I run the stock battery ignition. Still running 6 volt system.
I pulled it in our local pull and was beat by 2 C and 1 Super C Farmalls that were running weights. Our pull is strictly by plow class and not by weight and the Farmalls are a heavier tractor and pulling on 34 inch tires.
It is a really fun tractor to play with.