I use a chucking reamer- - - -drill bits DO NOT make round holes. Yes, just create a step in the ID of the tubing about 1/2" deep for the stub of the OEM pushrod to butt against, and keep the overall length reasonably consistent. The adjusting screw will compensate for minor variations in pushrod length.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!