I agree with using the brass threaded stems, rubber seal on both side of the hole will squeeze and conform to the odd shape of the opening. I have 22.5 tubeless on my '57 original wheels, brass stems, no leaks.

1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy