As an expert in Coffee, Tea and Chocolate, I would say that Green Tea does not have significantly more caffeine than Black.

Tea has more caffeine (per gram) than coffee! But all of this depends on how you prepare and drink your caffeine.

Caffeine is a mild Acetylcholinesterase inhibitor. If Mestinon does not work, then a milder version is unlikely to work, and brewing caffeine, varies and can give you wildly varying dosage.