If you have a vernier caliper, measure from the tip of the nose of the lobe to the back of the lobe.
Then measure across the narrow side of the lobe.
Subtract the difference, then multiply by 1.5. that should get you to the ball park of advertised lift at valve.
Make sure to check both intake and exhaust lobes to make sure that they are not different. Also try to check at least 3 of each intake and exhaust lobes to make sure that the readings are close.