Dont you have a 400w MH already? Just order an icecap 430 VHO retrofit kit, Two URI 24" Actinic bulbs, get some power cord, a couple cooling fans and start building. You can do it.
IF I were you, I would try to mimic the width of the base as much as possible. Use the same color scheme and trim as well. If you make it Tall and wide you will definately have the room for the VHO kit. Also, the URI lights have internal reflectors so you dont have to worry about that aspect. I like the look of the base in this pic. If its tall enough, you can do alot of routine mantainance without remove the hood through a front door.
I believe that only you can make something to match it.
I, personally would just use the whole pendant. It will be easier to attach it in the hood. Maybe hang it from a couple single link chains. As for the VHOs, get a piece of 1x3 clear pine, attach the end caps to it and hang it from the top of the hood with chains and eye hooks as well. That way you can adjust the heights of the VHOs where you want them. If you off set the eye hooks, the VHOs will hang at an angle directing the light into the center of the tank better as well. Now you are ready.
Its amazing what you can learn just by sitting by and observing others. I am setting up a new tank for sps corals and couldnt decide on VHo's or PC's to go with the MH's but now I think I will go with the VHO's.
Yes, 24"x24". That is why I recommend brain storming a way to make the hood a little wider, like the stand. Then you can put 24" VHOs in it without problems. 400w x 75w x75x =550w. Thats alot of watts over a 60G. I forgot to mention. Get two 1"x3"s and mount one VHO to each and put them on either side of the MH. Better yet, If you buy me an airline ticket. I will come down and build and wire it for you in a day provided you have the tools. I already have the blueprints in my head believe it or not. I've never been down south or east before. Just dont tell LA Lawman I offered.