Anthony,
You might try posting this on the Flattrack Community Forum. Up until I quit, you had to send the entries for a National quite early. If you blew up the bike, you were out of luck...unless you did what a lot of us Harley guys did. You buy a set of stamps. I had 3 KR engines with the same engine number. From the looks of your...6969 looks like something a racer might do to remember his engine number. Just a thought. A lot of old time racers go on that forum. Good chance someone there can help you.