I took these pictures some time back, but got distracted, so didn't get a chance to post (sorry).
My '77 has three stickers on core support, two of which are coolant related. Two of which are partially missing.
Without A/C
You can't tell but I get 5-1/4" wide.
The picture is deceiving, but this is 5/8" tall.
The other two stickers. Not enough to get measurements from.
Who did you order your stickers from?
BudW