Hello Mike,
when the W.Nr. was your source then you have an great problem
.
Regarding the Gzik thread he left the JG 300 in the beginning of November 1944 ... at this time the W.Nr. 490 642 wasn't produced. This a/c left the Leipzig factory an month later ... that means the machine used by Gzik in October 1944 couldn't be the W.Nr. 490 642 (and the photo show another machine then the mentioned "Rita" lost on January 14, 1945). Have a look in the Lorant/ Goyat chronicle and you find more then one "Rita".
Best wishes
Rasmussen