Looks like SoCal Mark may have been right, after all

... (I guess there's experience, and there's
Fiat experience.
Removed the engine block/transmission and separated them. The clutch disc still has some ID numbers silkscreened on the friction material, its that new. Ditto the nice machinings on the flywheel and pressure plate. What I had hoped was a faulty throwout bearing appears to be nice and tight; probably replaced with the other two items, which is customary.
So I've got a different (read; more expensive) problem. The car made a thrashing noise in neutral, and the problem went away as long as the clutch as depressed. That's a trip to the transmission shop, eh?