LED light fixture to replace metal halide over reef tank

I'm thinking of custom building a L.E.D. fixture to replace my metal halide fixture over my reef tank. I currently have 2 250 watt metal halide lamps. I've looked into buying one but the one I'll need is more than $800. I have way too much time on my hands and don't balk at doing this so...

What brand of LED should I choose? Where to buy? I'll need probably about 50 or so white and the absolute brightest, also I'll need 20 or so 453nm blue.

I'm also curious about reflectors and or magnifiers for the LED's
If also you have suggestions on power management, resistors recommended and proper heat dissipation I'm all ears.

I've built custom dosing systems for my tank and those of my friends and they love them. If I'm successful with this I'll again do the same. I'd like also when complete to put together an entire HOW TO video or guide for everyone to enjoy. I know I would appreciate a well documented one myself right now.

So please, any suggestions or recommendations to get started will be more than welcome. I'll also post my progress on this thread as the project moves forward.

Thanks in advance,
Jeff

Digikey.com has LEDs. They have a good help section.
Digikey.com---lighting solutions-----videos, designs, products, white papers, etc.
You could spent all night there and not get it all read.