ARCS5

First, thank you for anyone that can help. I bought this 2010 v8 in March and I have yet to drive it. The clutch was on the floor when I bought it and I had it towed to a shop to have the master cylinder replaced and then a extended slave cylinder (ECS tuning) installed. Then a new starter and ECS tuning motor mounts. This is what the mechanic states:

This is all when it is on a lift. He said the pedal is hard as a rock and that it wants to grind when you’re sitting there and going back and forth into gears (again this is on a lift with the wheels spinning). He also said that you could quick shift it to get it into the gears. He has already bled the lines and there’s no air in the lines. Main shaft is spinning and not stopping but it does slow down when you push in the clutch.

Any ideas?

Also, "supposedly" the previous owner says he had a used transmission (with 130k) installed and a new clutch and flywheel.