If you can only find a closed drum, try this method. A Weber 22.5" kettle has been sacrificed and lives to cook another day!
Cut the drum inside the rim
I cut the bottom rim of the kettle and make a flange that fits in the drum
Wrap a section of expando to fit the Weber coal grate, bolt it together and wire it to the grate. Optional-wire it to the old 22.5" cooking grate and it sits on 4 bolts above the intake vents.
I go with the three hole intake, but use whatever design you choose.
Cooking grate sits 24" from the bottom of my basket.
Mount your thermometer just at/below grate, paint and season! Now you're cookin'!