It's a function of my accel 300+ ignition box, I have it set to 6250, but it's variable every few hundred rpm.

This won't keep him from shifting from 5th into first, but it's not supposed to.

I'd worry more about missing a shift than taking the rpm too high. My engines usually get to a point where it's not worth holding the high rpm. set the limiter right around that point and teach him to stay in the good powerband.