Epoxy?

those instructions are exactly how I did mine (before even reading that) right down to trimming the underside with a die grinder, but I can stress that a mill or press is NOT required as the way the injectors sit in the bungs is on O-rings. The angles can be off a tad and they will still seat. But double and triple check the complete rail clearance before you drill. Usually you end up with them pointing straight up on a 45 degree runner. On a flat street Dominator style, good luck getting a pattern that will hit the valve. There is a guy on Ebay that sells AL bungs pre drilled for about $4 a piece in lots of 4-6-8.
Fuel Injector Bungs ( qty 8) - Aluminum Weld on EFI conversion Boss Bosch