Be careful with those brake mods. I'm not anti-mod, but do the homework before just throwing money at parts. Do you trust your (or other's) life with brake mods? If you don't maintain the correct bias you'll lock up too soon or not have enough where you need it when you need it. Again, like cams and heads/intakes, etc., you need a package of components that work together. If you want to maintain the stock look, the later S10 master cylinder will definitely look stupid on your Monte. The master won't sit at the right angle. They had ABS on those later S-10s where the Monte does not. So they're obviously designed differently.
Early S-10's share the same master cylinder as the G-body, so you want the "straight" style newer one like in the 2002-ish era if you're going to go the RH drive S-10 master cylinder route. No need to bother with the early model S-10s if you want that Raybestos MC390572, unless you find an early NOS one somewhere. If it's an older one, you can just swap resi's and you're good to go.
What I don't know, is if the RH drive S10 master is the same setup as the LH drive masters, with ABS and all that. There's no combination valve or anything on the ABS systems so it may not be a fast takeup master cylinder like the original on on the G-body. The 2WD S-10 uses the same brake calipers as the Monte, so that's a plus. I'm not an S-10 afficiando, so I don't know all that much about them and all the nuances about them.
If people are honestly having better brake performance without sacrifice somewhere else using the newer S-10 master, then that could be an option. Brakes are super-important, obviously. Just consider what changing component(s) can do.
