I don't think you need them to certify to 8.50, but to certify to 7.50, my 41 willys alston tube chassis B/P shows 1 1/4" X .118min. size, you also donot need a funny car style cage to certify to 8.50.
The 2008 rule book does not address this situation, but you are probably already aware of this.
I will install them on my Anglia rec. tube chassis built by A.R.T., but i only want it to certify to 8.50.
I know it's an addition expence, but the only way to know for sure is to buy the SFI 25.2 specs. or talk to an NHRA, tech if there's one in your immediate area. I'm lucky i have one about 40 miles away from me.
I'm sure someone of the chassis builders will come on here and shed some light on this subject, it was also addressed about a year ago here on this forum but i donot recall the real answer (old age
ops: )
Zip.