A 'calculated' 150 ft-candles is NOT overkill for a precision assembly/work area. IMHO.
It would be overkill for a sleeping area, a romantic dinner, a nightclub, or a movie theater.
Multiple zones are usually a good idea, as you can adjust the light level and to a certain extent the lighting direction as desired.
8 ft T8 bulbs are not as common or have as many choices in CRI and color temp as the 4 ft T8 bulbs AFAIK.
Speaking of 'color', I used to HATE fluorescent bulbs. Flickering, buzzing, humming, poor color rendering and so on. Gave me headaches and eyestrain all the time. That changed when I got some decent electronic ballasts and some full-spectrum (relatively) high CRI tubes to go in them.
So make sure you use 'decent' electronic ballasts and 'decent' tubes with good spectral qualities and a good CRI (which I consider to be 86 or better).
Shifting units, 1 foot-candle ~ 10.7 lux. So your 'desired' lighting level of 150 ft-candles is ~1605 lux. Which is about the lighting level of a cloudy overcast day (about 1000 lux). Full daylight but not direct sun is 10,000-25,000 lux.
Going back to lux and thus lumens, since bulbs are usually listed with a 'lumens output', let's see where you are with the total lumens theoretically being generated.
An 8 ft T8 bulb should be a 'theoretical' mean lumen output of about 5800 lumens (Sylvania FO96 T8). Times your proposed 40 fixtures x 4 bulbs/fixture = 160 bulbs equals a theoretical mean calculated 928,000 lumens.
Wow, you say? Let's try and adjust those values a bit into the real world. Light output from a fixture is usually 80% at best from the 'raw' bulb lumens.
928,000 x 0.8 = 742,400 'adjusted' lumens
Now let's spread those lumens over the floor space.
742,400 / (32 ft x 60 ft) = 386 lumens/ ft2
Since a foot-candle is the same as lumens/ft2, you are about 2x over your desired target lighting level.
That's also a lighting level of about 2x over the 'recommended' 100-150 lumens/ft2 for "precision assembly areas".
But you will have some additional lighting 'losses' and non-uniformity from the fixtures going up the cathedral roof from ~12 ft above the floor to ~18 ft above the floor.
So in summary, yes 40 4-bulb 8 ft T8 fixtures for your 32 ft x 60 ft space is a bit of 'overkill' in the lighting level. By about roughly 2x.
You can use that and just not necessarily run all the banks of lights at the same time, or you can reduce the total number of installed fixtures/bulbs and still keep them on multiple banks.
Your call and YMMV.
