I converted some mini-mags years ago, they didn't last long. I don't consider it cost effective to convert old flashlights.
Now I just buy LED flashlights or get the free ones at Harbor Freight.
I got a 3-pack of really nice bright ones at Sam's Club for under $20.
My super bright tactical rechargeable light sells new at flea markets for $15 each.
A flashlight built for LED will probably work much better than a retrofit the same as tail lights.
Build a life you don't need a vacation from.
2016 Silverado 3500HD DRW D/A 4x4
2018 Keystone Cougar 26RBS
2006 Weekend Warrior FK1900