Many of those numbers are from stock EFI Live tuning files I have so if they're wrong then GM has been selling truck with incorrect information in the tune for 10 years.
Here are the exact numbers(some will be slightly different since they're rated at either 43.5 or 58 psi).
99-00 injectors-21.767 pounds per hour
01-06 normal 4.8/5.3/6.0 engines-some I've seen have 25.2360 pph. Others are different for instance a 2006 stock 4.8L file I have has a scaled flow rate from 24.5-27.1 based on the amount of engine vacuum.
8.1L truck injectors- I show 29.9483 pph
8.1L marine injectors-41.6673 pph