There is a combination slide hammer/puller sold by Lisle that's made for pulling stubborn lifters. You need to pull the spring clip out of the top of the lifter and expand the internal jaws of the puller into that groove, then tap or jackscrew the lifter out of the bore. I'm going to wager you'll find the bottom of the lifter badly worn, and the part sticking out of the block above the cam is "mushroomed". Bottom line- - - -the lifter (and the cam) are both junk. There will be a corresponding amount of wear on the cam lobe. If the lifter is topped out and there's still clearance, chances are the cam lobe is worn almost round and the base circle is way undersized. Does the lifter move up and down as you crank the engine? Also check to see if the stud has pulled out of the head a little- - - - -it's just a press fit.

https://www.napaonline.com/en/p/BK_7769248

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!