Make sure you have the correct lube in your tranny. Mine had gear oil and I am convinced that was a major contributing factor in the wear on the synchros. When I got the car you really had to time the shifts to keep it from scratching. And it wasn't just me, I have shifted unsynchronized transmissions before. After I changed to Type A ATF the trans shifts much more easily.

I will probably end-up with Redline MT for lube, learned about here running some searches.

On shifting without the clutch, I assume that as long as you are not scratching the gears you are not doing any damage.

We had an old SAAB that had a freewheeling device. You could shift when it was freewheeling, just an automatic clutch.