AGO,
My friend Dénes Bernád, who researches Hungarian and Rumanian aviation, mostly World War 2, suggested that you will want to visit the Military Museum and Archives in Budapest. He gave their web sites as
http://www.militaria.hu/
http://www.militaria.hu/hadt.php3?page=500
He notes however that they are only in Hungarian.
Now, on my part, if you should happen to walk past a bookstore, I would greatly appreciate it if you would check on (and purchase for me if found) a book by Ottó Császár: Élet-halál a levegöben - Vitéz Szentgyörgi Dezsö életrajzi regénye, published by Magánkiadás in 1994 (ISBN 9634506003). I need it for my collection of aces biographies. I will gladly pay the costs for the book and postage.
Frank.