Are the numbers a progression of time? Or are you still able to rev to 7500 in first with the clutch in and the car not move?

If it is a progression of time, it sounds like clutch hydraulics to me. I would start by checking behind the boot on the master cylinder up by your clutch pedal, and checking the slave cylinder on the front of the tranny.

Well actually, I would start with a quick glance under the car for a small puddle of brake (clutch) fluid. Could tell you where to look next.

Edit: While unrelated to this issue, I would advise against synchromesh for these transmissions. The best stuff is Diaqueen, though lots of guys have had luck with MT90/MTL or a mix thereof for a cheaper solution.