Since you already have the bottom shield off, have some body depress the clutch and look at the disk. It should have approximate equal material on both sides at 1/8" to 1/4" thick. Since you can shift into gear with the engine running I suspect the problem is not the clutch.

1953 Chevrolet 3600
Fried Green T'mater (Vern)
In the Stovebolt Gallery
Caution: Political Statement
Man who runs in front of car gets tired, man who runs behind car gets exhausted.