The aluminum parts can be honed, but the rebuild kits are set up for the standard bore size. The piston in the rebuild kit would have too much clearance and the fluid would pass thru the gap.
NAPA had both pieces at one time so check the NAPA online ordering site to see if they are still available. AutoZone, PepBoys and Shuck's/Kragen's might be other sources.
Be careful with the hydraulic hose assembly when you remove it. It is no longer availabel thru GM and while Ecklers has a replacement, it apparently doesn't look exactly like the OEM one and the metal tube has to be bent to get it to fit.
Should anyone ever need to replace the hose, find a local shop that specializes in hydraulic hoses and have them make one. Beats the outrageous prices that Eckler's charges.
The master reservoir should be completely cleaned out before bleeding. I had so much junk in the one on my 87 that as soon as I filled it with fresh fluid, it was black by the next day. Bleeding is done at the salve end and you have to remove the slave and hold it level to bleed it. Not a difficult job just a pain to do if you don't have a rack available to get the car up so you can stand under it.