You are welcome, Keith. I assume that the relevant volume by Bernd Barbas may have some additional information about the combats of Heinz Ewald, I mean this title -
https://www.amazon.de/Die-Geschichte.../dp/3923457715
The LaGG-3 is by far the most likely aircraft that Ewald would have encountered, out of those that you mentioned. I checked sources concerning Yak-7 production and they state that the main factory which produced the type switched to the Yak-7b with a bulbous canopy from the fourtieth production batch in February 1943. It is not particularly likely that some older Yak-7s would have survived until 1944. The Hurricane had been withdrawn from the front by the second half of 1943, apart from the Arctic.
The larger point remains that it is difficult to assign much credibility to the aircraft identifications made by German fighter pilots. For example, Ewald could not have seen, much less engaged a single Spitfire in 1944. Soviet Spitfires were only used by a couple of front line regiments for a few months in 1943 -
http://lend-lease.airforce.ru/english/articles/spit/
Kind regards,
Dan