I didn't figure out the actual savings but it can be done with just the posted numbers. LED's use less power.In my case I replaced all of the 2x4 troffers in my existing stores and built my new stores with ones from the Home Depot.
A few year ago you had to buy them by the pallet but they have them in stock now. These are not tubes but LED strips. They are a disposable fixture but in most cases can be swapped out faster than rewiring and removing the ballasts. Also all of the light is directed down. Most troffers are designed to reflect about 60% of the light from the top and upper sides of the tubes.
You were typing that while I was typing my answer. Yes, it is very hard to get LED lights that put out equivalent lumens to fluorescent. You have to do the math. I did the math and argued with my engineer, he told me that there was an actual maximum number of lumens allowed by code in a commercial space and that the plans could get turned down.
I did what he said and wish I had put my foot down and just overdid it.