If the rules state a 26' rollout, (not a 13' half rollout or 6 1/2' quarter rollout), and your bike does that then you should be fine.

I assume they don't mention non-round cranksets.

Anyway, you should be in compliance... but, it never hurts to be prepared just in case some local official comes up with their own interpretation.

It also depends on the race. When my brother was at the Midget State championships on his little 24" bike, some kid showed up with a 700c bike. So the race officials just asked all the kids and dads if he could race... what could one say? Anyway, the kid raced, and I think placed #2 . It wouldn't have been allowed at the Nationals.

Anyway, rules and age categories have changed since then.