Questions on lifter bore correction

[GallopinGhost]

I'm trying to justify the cost to have this done on my block. 383 big block mopar, stocker.. I've heard costs are $500-700. If correcting the angle and location is worth 20 hp, then fine, if it's getting 3 hp, I'll spend the money somewhere else. Also, when this is done, is the oem angle kept....?

I'm on a budget and want to qualify with a little headroom, not kill it. thanks.