A833 shift proplems

My first guess would be the shifter gates. Yes we know you did that but double check.

All shift levers on transmission in neutral, linkage rods off, Pin the center pin on the shifter so that stays in neutral while making the shift rod adjustments, adjust the rods to proper length and put it all back together. See if you can find a picture of the proper shift rod layout for that trans. Sometime the rods can get swapped around and that changes the geometry of the lever swings.

Next guess is to make sure the clutch will fully disengaged with 3/4" free play at the top of the pedal. Quick test is to put the car on level smooth ground, shift it into first with your foot all the way down on the clutch pedal. Start the car, if the car wants to slowly drag forward without your foot on the brake, then you know your clutch is dragging and needs adjustment. 2" of free play at the top of the clutch pedal can be a sign of this problem needing adjustment.

Worn shifter forks inside the trans can be an issue too. Want all the internals in good shape with the gear slides leading up to the sincros.
Bad sincros and worn gear slides are a big cause of bad shifts. The worn Brass Sincros cannot grab the gear anymore and get it up to speed so the gear slide will line up, so ends up hard to shift.

There is a start for you . . .