Building a light from a light advice

[reefwars]

Tonight I'm going to strip down my 6' aquamedic metal halide, and turn it into a 3' fixture and build it into a canopy . I've never done this but do k ow some basic electrical from work, tonight I'm going tower what makes it tick and I plan two use one metal halide and two 3' actinic. The light is old and two of the three mh are busted where the bulbs are held In place.

Any tips or tricks or things to take caution of??

On their site(aquamedic) they say not to use in canopy because of ventilaion if I make plenty of ventilation is their any other reason they would "recommend" this??? Thanks sparks are gonna fly