Not meaning to cast aspersions, but is he entitled to be regarded as a Battle of Britain fighter pilot? The first Squadron he was posted to was 32 Sqdn at Acklington then to 46 Sqdn at North Weald in November 1940, technically after the end of the BoB.
Taking nothing away from him or his achievements, just asking what qualifies someone for a BoB entry.
The American Air Museum in Britain gives his Nationality as "American"
http://www.americanairmuseum.com/person/238463 with a Service Number, and presumably he's in that group photo.
You might also want to contact Franek Grabowski who posts on the Military Aviation section of PPRuNe and appears to have many details of WW2 Polich airmen.