I'm spinning right now. Can you recommend a fixture? When you say f54t5 are they all the same? I don't mind spending a little extra where it makes sense.
For shadow free fixture placement, assuming your purlin locations are similar, use "Y" dimension locations from the 40x60x14
#41 &
#42 pattern except continue the fixtures above the interior room. That layout has 12' walls and uses custom built T8 fixtures. You'll want to substitute F54T5HO. Yes, F54T5 is the same as F54T5HO.
Place three 4ft (actually 46" long) end to end, centered between each support in the "X" direction. So that's 3 fixtures x 4 spaces = 12 fixtures lengthwise. 12 fixtures x 4 rows = 48 fixtures total.
2 lamps per fixture = 96 Lamps.
Suggested Fixtures and Lamps:
Qty. 48 Lithonia ZR 2 54T5HO MVOLT 1/4 GEB10PS - $
43 ea. @ HD.
You'll have to do your own research to determine ballast quality, plus you could use 1 tandem + 1 regular fixture mounted end to end. Here are the other contenders available at HD (obviously there are lots of alternate brands and places to get them):
TZ 2 54T5HO MVOLT 1/4 GEB10PS
TZR 2 54T5HO MVOLT 1/4 GEB10PS
Z 2 54T5HO MVOLT GEB10PS
Qty. 96 Sylvania
20949 F54T5HO 5000K $
4.68 ea.
The 30,000 hr. life on the site is wrong. The most current Sylvania spec sheet (linked) says 40-45,000 hrs.