I bought this kit, just itchy to get another F104, and couldn't resist a classic F1. Didn't like the rear rubber, and no problem of finding a suitable foam for it. Just use foam for F103 chassis, and no problem. The main concern is the front, as most foams for F103 are bigger and wider than the stock rubber. I don't know if the option foam for Tyrell 6-wheeler will fit nicely at the front since they are smaller in size compare to the normal front foam for F103...