833 OD sticking in 4th, chipped synchro

I do not think moving the M/S forward is an option in that trans.
>As to the front snapring; I do not recall the thickness of the factory ring. .064 sounds a lil thin, but I just don't remember. So;
lay the gasket onto the retainer and slip the big snap ring into the receiver-step. Make sure it sits below the gasket. It has to sit below the gasket, else either the retainer will break when you tighten it up, or it will leak.
>By the same token;
If after you mount the input gear into the case and bolt the retainer on, the whole thing moves back and forth, something is wrong. and most likely would be that the wrong thickness gasket is being used, but could also be a too-thin outter snapring. So figure that out first.
Your goal is to move only the input gear back. Once the correct relationship is restored as to the large snapring, then you can see about the small one. Here your only choice is to put the thinnest snapring that you can find into the groove, and move the bearing up tight to it, then measure between the input and the bearing, and install whatever shims you can get, into there. I used to use rear-end shims, left over from the days I was a rebuilder, some 40 years ago..
Now, before you spend a lotta time on this, consider that you're not gonna get much. It is usually much more advantageous to just install a new hi-riding brass on both of those gears, which will instantly restore the inter-brass distance, to the factory measurement.
>And once again I highly recommend NOT to install any synthetic oil into that box. It is too slippery, and will either delay your shifts or else you will get impatient and ram it into gear, which will chip off your clutch teeth. I use 50/50 Dextron-II and EP 85/90. You can use whatever EP oil you have; just make sure it does NOT contain any additives for any type of Limited Slip Differential. This EP oil is only in there to protect the Cluster pin.

>Finally, that od box has very-wide ratios, same as any Mopar 3-speed, so it's NOT a hi-perf box, and so; don't try to get hi-perf out of it. If your engine is slow to rev or more importantly the revs don't fall in a hurry, either fix that, or go easy on the trans.
>The ratios are; 3.09-1.67-1.00-.73od with splits of; .54-.60-.73.. The regular
4-speed is .... 2.66-1.92-1.40-1.00 with splits of; .72-.73-.71
What the splits mean, is that at whatever rpm you out-shift at, the in-shift rpm of the next gear will be at those percents.
Say you outshift yours at 5000 rpm;
54% of 5000 is an in-shift rpm into Second of 2700 for a drop of 2300. Now with the regular 4-spd, still outshifting First
at 5000, your inshift into Second will be to ... 3600 a drop of just 1400.
So like said, yur gonna have to wait for the Rs to come down.
The picture is only a tiny bit better at 3000, the Rs still have to come down to those percents.... so you still gotta wait, just not quite as long.
>After reassembly, keep after your clutch-departure, so the brass doesn't have to work so hard, trying to slow the engine down. This means; keep your hand OFF the shifter, except to shift, and don't bother downshifting into direct, unless circumstances require it. Be nice to that brass and it will last a really long time. Another thing to keep in mind is if the car is slowing down too fast. This could be due to; dragging brakes, very low tire pressure, excess baggage/towing, terrain, or road surfaces.

If your engine is slow on the deceleration, my guesses are;
A heavy flywheel
lack of cylinder pressure,
insufficient clutch-departure
throttle open too far
running too rich
lack of timing advance.
Lord help you if she has all of those problems, lol.