I do my own machine work, to tolerances in the +/- .0002" range, routinely. I've never had problems holding those tolerances for the past 40-something years. I'd choose 304 stainless tubing, finished inside and out with a tool post grinder. .040" wall thickness on a sleeve the size of a lifter with the proper press fit wouldn't be a problem at all.
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!