Wow, that's some pretty stuff. Interesting that the engine is solidly bolted to that subframe, and that Offy-style exhaust must really make some lovely sounds. That sure looks like an S4 block ('91-94), so a starter from an S4 Spider would be the way to go. You should call APE and see what they've got available. ~1.5 years ago, I bought a nice used starter from them for $100 shipped. The Bosch starters are really quite generic, and most local rebuild shops should be able to supply bushings, brushes, etc., if required. Here's APE's site:
APEDIRECT.COM
Not sure about the cylinder head, though, because the cam cover is from a much older car (i.e. pre '75), and there's no VVT (variable valve timing) solenoid on the drive end of the intake cam.
Has the 009 distributor been recurved from it's VW settings? Here's a great alternative, with multiple selectable curves, and it will work with the coil you've already got:
Alfa Romeo Parts and Spares www.highwoodalfa.com
Where'd you source that nice oil filter plate with the oil cooler fittings?