Partial answer to help bound the values:
The SA-507 Flight Manual page 3-9 says the nominal meter indications shouldn't exceed 25% to 50% of the limit. With the max nominal numbers in the other answer of 20 kNº/m^2 that puts the limit somewhere between 40 - 80 kNº/m^2.
I have not yet found the abort limit figure.
According to Saturn V AS-507 "G" Mission Launch Vehicle Operational Flight Trajectory - September Launch Month (a trajectory planning document for Apollo 12), the peak Qɑ for a nominal flight would be between 18 and 22 kNº/m^2 (= kPaº):