I could use some advice on Master/Slave cylinder issues...

THE BULL

So the beauty of the clutch system is that it's a small one and rather fool proof until it is not.

I mean fluid quality will be the first giveaway. Overall for this car FLUID QUALITY is the rule you must go by in other to catch these issues ahead of time.

The issue with the clutch is that damn black rubber hose feeding the master, time and time again it have been documented of their deterioration.

Hit up Mike Upton on FB he sells a clear hose intended for brake fluid that wont deteriorate. After the hose you should bleed the entire system and test.
With the new hose and fluid you might save the concentric slave.

The main reason why you had an issue with the clutch at such an early mileage is because this car sat, for a while. This sitting just turned that hose into jelly and that Jelly killed your MC since it's the closest to the reservoir.
Your slave might be OK since most of the fluid in the line was clean and the system usually uses the oil that is past the pump to move the slave and this oil for the most part was clean. Bleeding introduces the old oil for a bit but clears up so again I think your slave will be ok for now.

It wouldnt surprise me if you kill another pump by the time you kill the slave.