These kind of tractors are great for pulling! The only thinkg I would change would be the motor. Reason being because you can not any performance parts for them when needed unlike the kohlers everything is already made for them.
Another plus you have there is the HI-LOW transmission. Most of the guys in our club are just running high but just depends on you club rules.
Make sure you find ya a local club and pick up their rules if this is what you are wanting to do. Here are some pictures of guys in our club running sears-