somtimes when installing the shifter if ever part is not lubed enough or if certein parts are installed differently it will cause the shifter to feel funny.
however if your grinding at just 133,000miles how do you drive? do you have a counter weight shift knob (heavy shift knob 1-2lbs)? is your pedal engagement/shifter engagement on timing with each other (not that i dougt your manual driving skills its just that somtimes changing somthing can throw off your timing)?
1st i'd try bleeding the clutch slave. seeing how that goes if it truely is somthing internal mechanical i'd try the fluid that was recommended. do all this before thinking about rebuilding the tranny.
incase you don't know whats involved in a tranny rebuild i'll give some insight. you'll need a XXXXXX ton press, followed by certian SS tools (special service tools) that you'll need as they provide the only means of removing certain bearings without damaging anything. you'll then need a bgb or a diagram of how the tranny is disasembled and reasembled followed by tq specs. seals, syncros and bearings usaually total aroung $400-600 usd (lsd time maybe

or even cryod treated). labor for a tranny is about 10hours however it'll take 1-2 weeks maybe even more depending on if you break or have to preload certain parts that need certain size shims.
if your rebuilding yourself look to take 2-3weeks on the project. a tranny rebuild is actually stright forward and you can actually test to see if everthing works before you decide to drop it in the car. as i said the rebuild process is not long its actually waiting for right parts. also try to aim for bearings such as koyo and equal or better quality.