It seems like something on the input shaft, as the noise starts and stops with the input shaft rotation, but then it kind of sounds like it might be something at the clutch parts, like something rubbing but I'm not sure what.
Time to start pulling it apart again... look for any scraping marks around the clutch parts to indicate something hitting when it shouldn't be, then go to the trans. Spin the input shaft over out of gear, feel and listen for any noise in the bearings. Check the oil, look for contamination. If you hear/feel something in the trans on the bench, pop the 5th housing off and have a look, debris almost always gathers in the 5th housing behind the green end cap.
Does it select the gears fully with the engine off?
With the engine running, what does it do when you try to select 1st and take off?