How far to rev this 273 commando build

Download a G-meter app onto your phone.
Get one that works off the accelerometer chip in the phone, not GPS.
Tape or secure the phone near the tach, where they are visible.
Boot it in each gear, - note when the Gs drop, that was your shift point.
Don't be surprised if it's different in each gear.

Hydraulic lifters pump up from lack of valve spring pressure.