Not like you can go to JC Whitney and get whatever you want for them these days. When I was a teen I helped a neighbor with his Midget. I forget which racing organization it was part of but they had like a 3.5 litre limit on the engines. Numerous 21 stud Flatties ran with them. Probably would have been competitive if they had been in more modern chassis, but they were in older evil handling vintage cars.