Sprocket Sizes?

This is not really a motorcycle question but I figure you guys would know the best answer.

I’ve got a go-cart with a 5.5 Hp Honda motor on it. I’ve recently used the cart as a platform to build a small parade float on. It’s been working fine but I’ve noticed that with the extra weight on the cart that I need to replace the centrifugal clutch and make some small adjustments to how it’s set up.

Right now I have a 10 tooth sprocket on centrifugal clutch on the motors drive shaft and a 72 tooth sprocket on the rear axel. I need to replace the clutch and I’ve got access to ones with the same 10 teeth I have now or I can "upgrade" to one with 12 teeth. It’s also been suggested to me that I switch the sprocket on the rear axel to one with 80 teeth but due to the way the cart is built that will be difficult (but not impossible) for me to do.

Which option will give me the best improvement? Changing the smaller or the larger sprocket…or perhaps both?
Just to clarify, speed is not so much an issue for me since I’m only driving it slowly in local parades. I’m more concerned with not over stressing the motor and having it smooth running if that makes sense.

If you increase size on small sprocket it will give you more speed, if you increase the 72 to a 80 you’ll get more acceleration off the line. You want to go with the 80 tooth, or a smaller than 10,