I got the manifold off with another soaking of PB Blaster, loosening the pinch bolts at the center muffler, and some whacking with a rubber mallet and an extension at the manifold/downpipe joint.
The heat shield looks to be in good shape - no flaking material or egregious rust. I might give it the Horsewidower treatment and polish it, just so something under the hood is spiffy. Even if you can't see it.
Turns out the rebuilt starter I picked up fairly inexpensively had the wrong solenoid. Not the run-on condition one, a 4 wire one, I think for a 164. If it works for one Alfa V6, it'll work for all of them, right? It bolts up fine, so I've got that going for me.
I found a spare starter in my father-in-law's garage, but testing showed it to be on its last legs, so I'm debating pulling one of the solenoids from an old starter to put on the rebuilt one. I'm not sure how to test the solenoid to make sure it's still in decent shape prior to putting into service. The other thought is to get the proper solenoid and install it. One question about this - how thick of a shim is needed to prevent the run-on condition? The thread I found about this didn't answer that.
I plan on rebuilding one starter so my f-i-l and I have spare on hand, if needed.
So, lots of work, no progress.