In our main workshop, I replaced 3 x 36W fluorescents in one fitting with 2 x 18W LED strips and checked with a light meter. The fluors gave a reading of 89 units, the LEDs gave 88, so I did the same to the other 8 fittings, then another 6 in other work areas. No complaints about brightness.Having got it all working you will find the LED tubes are not as bright as the florescents you removed, so why bother.
Look up the lumen output the LED tubes and compare with the lumen output of the same size fluorescents.