[Nick Beale]

I can confirm that there wasn't a dog fight, I spent 8 years working on a book about the Axis air forces in Italy. the only German or Italian daylight activity I and my co-authors found for 22 April was a recon mission by an Ar 234.

I'm no expert on ground forces but for records of German forces in the area (essentially lements of the German 10th and 14th Armies) you're probably going to have to try either Bundesarchiv, Freiburg (they have an online file index) or possibly the Imperial War Museum Department of Documents. I don't know what the USA has.

You could start with the bibliography and source notes in one of the serious histories of the Italian campaign to see if that gives you any leads.

If you want a picture of what the Allies were up to, National Archives file AIR23/6513 will give you the daily operations/intelligence report.