Helios and Mega6 are 2 5W-based dropins for Mags from Inretech...
Otherwise, you can choose to mate a 5Wer to a PowerPuck and have a regulated light. Or you can choose a BB700/BB750 converter board and mate that to an LS... Or you can just do the Mr Bulk way: Direct Drive it... I believe Elektrolumens had a post on how to mod a Maglite... You can try doing a search on the Homemade/Modified forum...