We used 4x1000w, but this tank is a tad shorter and shallow.
30" is a nice depth. More typically means access issues, but the depth vertically is very nice in many respects.
I'd go 400w x 5 maybe 6
I measured 220 at the farthest reaches on the bottom up to 880 umol PAR in the behemoth (see other thread) we just did with the 4x 1000.
They are about 18" above the tank surface.
This allows you to get in/out easy.
But also better spread front to back.
Using these, do not be too scared to have them higher.
400w offers more bulb color options, electronic ballast(MH ballast are loud!!!, E ballast are not).