For your odd shape tank, you might need to be really creative to get enough light in .... retrofit kits in a custom canopy is prob the way to go.
T5HO's are your best bet, but I don't know how many 24" (24W) you can squeeze into your foot print. You might have to use some power compacts in the shorter end.
BTW - if you are doing reef, you prob should get an aquarium fixture. Light output of the T5HO's are dependent on the quality & shape of the reflectors. HD fixtures have reflectors meant to spread light throughout a room. In a tank, you want polished aluminum reflectors that directs all the light straight down into the tank. <Although you can gut a spotlight type fixture, get good reflectors & install that in your canopy, it is not cost effective for T5HO's.> I run a FW
planted, and my HD job works reasonably well. I don't know enough about reef to say how you can DIY a fixture, esp. when space is tight and you can't put in extra bulbs to compensate for inefficiencies.