Finding the right fit is sometimes frustrating paying for return shipping ect. Do not buy a Tiltit it puts all the cornering pressure right on 1-2 ribs and it will mess up your back. Get a ribtech or a deepseat they both have sizing charts.
Chassis parts that are branded with the kart name are the most expensive. You want the CKS Billet Aluminum Sprocket Hub. I’d stay away from floating sprocket mounts and anything wild.