I'd make a midi UDS out of that 30 gallon drum if you haven't cut out the bottom already. Look for a donor 18" weber kettle on craigslist etc. The lid from the kettle will fit on top of that perfectly. Then you can use the cooking grate and charcoal grate for the project too.
For less than $100, you'll have an awesome cooker that will work just as well as a WSM.
Oh, and never paint the inside of any cooker.
Modded Brinkmann Gourmet. Basic UDS. Rescued 22.5" OTS. SJS Mini-WSM. Stubbs. B&B Oak Lump.
Cannondale 2009 F8 (for burning off all the great BBQ)