Howdy Josh, welcome.
Is funny, eh? the kid at Christmas effect.
Some fine choices there.
Is this the one you are looking at? I have no experience with it but some one will.
Freewheel Sprocket & HD Axle Kit w/Brake Freewheel Sprocket & HD Axle Kit w/Brake - $49.99
Kit includes a freewheel sprocket, heavy duty axle, and drum brake. For use with StarFire and SkyHawk bicycle engine kits. Please specify either 44, 48, or 56 tooth sprocket.