Problems going back in to gear after..

Have you adjusted the freeplay/clutch-departure* when hot?
Are you running a Full-synthetic oil**
Like already said, if the clutch is dragging; when the car is stopped, the brass cannot synchronize . When the oil is cold (regular SAE 75/90 NLG) is viscous enough to drag the cluster to a stop; but as it heats up, it can no longer do it.
Reset your clutch departure and it will be fine.
Slantys have a different pedal ratio than V8s so if your car is a V8 (10.5/10.95" clutch) but was originally a slanty (9.5" clutch) and the pedal seems awful hard to push down, now you know why.

* Clutch departure is how far the Pressure Plate pulls off the clutch disc. For three-finger clutches you need about .080. Diaphragm clutches MAY be able to get away with a lil less.
The way to check this is to first reset your freeplay to about 1 inch or a lil less. Then have a helper push the pedal down , while you install two feelers (.080) as close to 180 degrees apart, thru the PP windows. Once they are in there, have the helper back off the pedal a bit to put a squeeze on the feelers. Then , while you are tugging on the feelers, have the helper slowly push the pedal down, again and ask him to stop when the feelers are released. I like this to happen long BEFORE the pedal gets to the floor; but whatever the distance is, that is how far, AT LEAST, that you will have to push the pedal down.

**BTW; IMO;
Full-Synthetic fluid is TOO slippery for most A833s . If you have some in yours, I highly recommend to flush it out and go back to NON-Synthetic; standard EP-oil like a 75/90 ( I think NLG) which does NOT have any additives for a Sure-Grip/LSD/posi/ whatever.
At one time I really tried to make my A833 to be Synthetic-Friendly. I tried everything I knew how to do. I had that trans out several times in the same week, twice on the same day! Nothing really worked, So I put the 75/90 in it and BadaBoom! , it now shifts like lightning.
Some guys say it works in theirs, but they haven't seen mine shift; so IDK, lol