What's the MAX blood sugar spike a non-diabetic person could have that's still considered normal, i.e. shortly after eating, a high carb meal? 200?

Not standardized. Hi. Finger stick blood glucose measurement is not approved for diagnosis, and there is no standardized value for "shortly after" "a meal". The standard for a challenged glucose is the 75 gram oral glucose tolerance test done in the fasting state. 2 hours after a 75 g glucose load, serum glucose should be under 140 to be normal; over 200 is diabetes; in between is impaired glucose tolerance.