I'm with Rusty Nail. And that K25 of yours should be called "Rusty Bucket!"
But, if you were to shitcan the engine and LS swap it, it would all be good?
well, technically, maybe.
If you removed all issues from powertrain(assumed by doing a swap) it only needs maintenance and creature comforts.
Creature comforts being rust removal(frame), body panel work, a floor, cosmetics, paint, a new hvac controller thing, a new set of sliders for it, a radio that doesnt have to be punched, new plastic for the gauge cluster + a new needle for volts, weatherstrips, brake line, fuel tank, etc..
you know, the small things.