3 480's would be overkill. But that's not a bad thing. They have dimmers.
Basically you want around 35w a sq foot. But lm301 quantum boards seem to do better than your average led fixture.
4x8x35=1120
480's would be easier to setup with only 2 fixtures and 960 is close enough for lm301's. But... we are suggesting using 240w fixtures so you an spread the light out more evenly. They also cost a bit less and shipping isnt as bad cause they are smaller. Also if you get 4 or 5 units, you may be able to get a deal.
Ultimately it's up to you, yes 2 x 480 will work, but it will be JUST getting you there in a 4x8. 3 is much too much and you would be dimming them, which is good for the lifetime of the fixture.
If it was me, I would get 5 240's and hang them longways evenly across the 8 feet. That puts you at 1200w giving you 80 excess over the 35w sq ft rule. As they are lm301's and seem to put out more light per watt than most LEDs, the 35w per sq ft rule should be more like 30w per sq ft. So you would dim them down still.
Good luck
if you meet the wattage requirements, it's more about spreading that light evenly across your footprint to get a full, even, and consistent canopy.