See then you completely understand why my wife would kill me if I mounted a ceiling hanging metal halide in one of the formal rooms... If you have a canopy... make sure the lights will fit and you can still get into the tank for maintenance, feeding, etc... If the canopy doesn't work, this could be the reason to upgrade or remove it all together.
As for VHOs... they produce the least amount of heat between the three... so this alone will be worth it weight in gold.
Rememeber that the bulbs will have to be changed about every 6 months. Yes the bulb will still firer, but the wavelength with only be good for growing algea and stunning the growth/slowly killing your corals. Unless you like algea, if that is the case run the lights 24 hours a day and never change them.
Since the tank is only 37" wide you probably will not be able to fit the 36" bulb with the end connectors... But three 24" bulbs will still give you 225w (75w each). That should more then enough lighting for soft corals, polps, mushrooms, etc.
As for the ballast... try to go with iceCap - I have never heard anything bad about the company and they are working great for me.
I you have any question... you can always email me directly...