I'm doing it a bit different. I did the 5050 strips in the fixture and was so displeased with the illumination I yanked it all out and went back to fluorescent. I found a guy in Quartzsite selling LED strips like I hadn't seen before. These are multiple LEDs on a thin aluminum strip. I found some on eBay that were 1/2 his price, so I bought a pack of 10 strips, enough to do all my fixtures, and they are bright! I ultimately didn't like the color, so have ordered another pack @ 2700k rather than 6000, but I ran one of the 6000k strips in the lab supply at 12.6v for 24hr and the strip was warm but not hot. For the overheads I WANT bright since these are nothing but maintenance lights for loading, cleaning, etc. I've already bought heat conductive adhesive (clue) to attach these to the OEM metal case, effectively turning it into a heat sink.
These are the LEDS: http://r.ebay.com/JRIOnk