My first post was more for your other thread.
When you’re looking for a 4 cycle chassis you want more flex because the tires are harder and the horsepower is lower. Generally, you are looking for an SL chassis because we are running an SL type tire. For example, Dunlop SL-4 tires. If you get a stiff chassis that is made for higher horsepower sticky tire class, it will not turn very well for you. American karts will have tubing sizes from 1 1/8″ to 1 1/4″. The euro kart have 28, 30, 32, and 40 mm tubing. If you go euro stay with a kart that is a combo of 28 and 30 or all 30mm. If it is 30 with some 32mm, it may be ok with the high horsepower limited modified animal.
Because Shifter karts are faster into the corner they run the 3 disc brakes and a stiffer chassis. With 4 cycle racing you try to stay off the brakes and use corning (turn in) to slow down. So the front brake are extra weight and money. The stiff kart will not left the inside rear and you will be pushing in the corners.
IMI had two or three used Margay Brava 4.x for sell. Any Margay that has a 4 in it is for 4cycle. They also have Coyote wide tracks. I think it is the east coast WKA Gold Cup chassis of choice.