Clutch won't return off floor

You talking about a BB pressure plate? This has been a problem since the beginning of time with Mopars. I "had it" back in the early 70's with my 69 383 and my 70 440-6 car. Careful clutch adjustment helps

What you are feeling is this:

The Great Big Spring under the dash pulls DOWN after the clutch pedal goes about as far as you describe.....1/2--3/4 " or so. So then it tries to push the clutch down, and won't "pop up." Less free play in the adjustment helps this