833 Rake between gears.

Take pictures!
Mine has 2nd and 3rd slick-shift mods but I left the slider splines alone, allowing me to keep the brass rings in there for street shifting. When "racing" it is easy to overpower the brass and slam it home.
Perhaps yours can be modded that way too.I sure wouldn't replace any gears if just every second clutch-tooth has been removed.

As to the upgrade ; IMO, for a streeter,Switching to the later stuff is only on the table if your parts are in poor condition, or you're made of money.So for you it might be a good option, if the synchronizers have the full Slick-shift mods.
But if the hubs and sliders still have a full spline count, then you just need a set of brass rings.
So if you post some pics of the hubs and sliders, and clutch teeth, I might be able to walk you thru making it serviceable, and shift like lightning, too.
Then again Jpar might have parts to swap.