Yukon HL already has a Luxeon. I've modded the regular Yukon to LS only because I have very specific beam profile demands. I am using Fraen 10 degree optic, and I plan to nest a 5mm inside it. The Fraens (not the LP) have holes in the middle that a 5mm can fit into if you grind part of the lip off. I'm debating red or cyan.
Anyway, it's not that straightforward, and I wouldn't bother unless you prefer some sort of optic.