Two ways to remove the over center spring. Pound washers, alignment shims, etc between the coils when the spring is extended. Then move the pedal the other way to shorten the pivot centers and pop it off. Or loosen the pedal assy bracket (brake/clutch) from the fire wall. This will allow the clutch pedal to move far enough to easily remove it. I'd go this route and install the auto trans stuff. Then sell the clutch stuff.
Doug