Probably a good idea to read through all of ErikB's brake page before throwing assorted parts into the brake system:
http://home.4x4wire.com/erik/4runner/brakes/

There is a fine balance between all the parts in the system and bigger may not always be better. A bigger m/c pushes more fluid with less pedal stroke, but with stock size brakes, this will just make for touchier brakes. Also will make the pedal harder to push. Add the dual diaphram booster and you get more brake boost but that can make things touchier. If you add bigger brakes (i.e with larger or more pistons), then upgrading all the above parts make sense. Do less than that and you need to be a little more careful in the selection of the parts. Erik documents his adventures in that area (he started with larger front brakes due to his SAS).

I am currently doing this swap on my '85. I have large 4-piston Wilwood calipers up front (stock m/c does not push quite enough fluid for these, it bottoms out too soon) and will be adding rear Supra discs. A 1" FJ80 m/c will be installed as well as a T100 dual diaphram booster.

But as far as boosters, I think most any of the single or dual diaphram boosters will swap. The duals are a little thicker and will need brake line tweaking, but the bolt holes and fittings are all the same. So an early '90s vintage FJ80 master will bolt up to a '97 T-100 booster and all that will bolt into an '85 4Runner.

In fact, once I finish up that swap, I'll have a stock booster off my '85 available if you are looking for one. Might be a month or two before I get that swapped out, though.