Use 1 watt/sq ft for estimating.
(29)(51)/(40)= 36.98 or 37 lamps.
So it gets down to any combination that allows even distribution of fixtures.
What about 3 rows, 10 ft apart, along the 51 ft dimension, mounted 10 ft high? (36 4 ft lamps or even 18, 8 ft lamps)
No consideration given to shelving, etc that might block out some areas.
Lew