Do these fuel burn numbers sound right for a 454 powered 89 3100 open?

[Lured Away]

I had a 1988 with big block crusaders and had installed a Twinscan. If I recall the secondaries opened up right above 3250rpm (you can hear it when they open) and it would jump up to 15-16 GPH  per motor.  If you can keep out of the secondaries around 3200rpm it burned 11-13 GPH and ran 21-22kts.  I tracked the fuel burn over the years and was pretty consistent.