[Yosemite Sam]

I gotta agree with Roland, if you go speeding things up, everything better be in excellent condition, including all the parts in the gearbox and everything associated with the chain tensioner. It's a lot cheaper to rebuild these parts first rather than replace them after they explode.

Using a smaller pulley is also going to cost you some power, your 10 hp engine may not be able to handle the extra load.

If you don't have a creeper, I believe you're going to have a hard time throwing snow, your ground speed needs to be fast enough to keep the housing full of snow but not so fast that you end up pushing the snow.