Thank you so much for the response. It was very helpful. I modified it to look for Google's mail API generated email:
header LOCAL_GMAILAPI Received =~ /gmailapi.google.com/i
Everything else you posted remains the same. It was looking like the spammers were measuring the Spamassassin score before sending so this now pushes the score where it belongs. At least until the next time.
I also found milter-regex will let me reject email when added after spamass-milter. This lets me reject spam email from gmail.com only. I use the following configuration:
reject "No thank you"
header /^From$/i /gmail\.com/i and header /^X-spam-Flag$/i /YES/i
So far seems to be working.