Would you count beta?.. its not the actual thing imo
Absolutely, most records are the product of the age they were set in. Will anyone ever win the triple crown in baseball again? Or will another player ever have a 56 game hitting streak? Getting 354 kills w/out losing an aircraft is a significant milestone regardless of when it was done. It was also accomplished in an aircraft that was not exceedingly dominant in a single category like the 262 is now, if memory serves he flew the 190A8 primarily.
*edit*
I'd be impressed if someone got that many kills now in a 262 or otherwise, I just used the 262 because it is so much faster than just about anything else in the planeset and thus can do more to stay out of trouble with good SA.