how much boost could i run on a 5sfe (1992) using the stock internals?

This is an unanswerable question.
Boost from what? Name the specific turbo / supercharger you want to use. You can't give a psi range.

There is too large a mass, differance between different units.

Historically... You would do very, very good to get 230hp reliably.

Someone that actually *really* knew what they were doing might get up to 250hp using water injection, and other vairous tricks. But that would be for short uses like a drag race... You could never daily drive that. Only rarely is 230hp reliable enough to daily drive. I am thinking of two examples off the top of my head, and maybe a dozen others that have melted pistons, and rings in failed attemps. Be it mechanical failure, or tuner error. The stock S-FE blocks don't have the piston / ring strength to make big power.

The 5sfe can take about 7psi of boost on a good bone stock engine. With the right mods, a 5sfe can take 14psi and still be a daily driver. I'm in the middle of a 5sfe turbo project myself. Here's site that can help, http://warp.scl.utah.edu/mr2/turbo5sfe.html. It has more info than I can give. Good luck!