Useful tool idea?

Jegs shows what they call a "Louis Tool" (p/n 249-4710 costs $33.99) in their current catalogue on page 39-N. It's a tool steel drill bushing with an offset hole that fits in the pushrod slot of a SBC head to allow you to use a hand drill to elongate the slot for going from 1.5 to 1.6 rocker arms. It might or might not be usable for opening the pushrod slots in a 300 head for 1.75 arms, but it certainly could provide a pattern for a tool that could. If it fits or can be made to fit the 300 head it might be worth the $34.