Holy cow, this is like bizarroworld. I just created the same exact setup last week after never having seen it done before. Today I was perusing correct pizza oven dimensions and stumbled across this post so thought I'd register and post up my creations! You know what they say, great minds thinks alike!
Started with the same 55g steel drum
Cut it up, installed hardware, added hinged cooking grate, etc...same as you
Thermometer and cooking grate
Test burn-in. Pegged the needle at 700* for over 8 minutes.
Made our first pie with it!
And I even made a smoker out of the remainder!!
I named the pizza contraption the "PizzaBarrel" for obvious reasons. I'm very pleased with the outcome and the product it delivers. Im going to make a few more and sell them at a local market I think. Right now Im researching ideal dome/vent dimensions and ratios and doing a bunch of small test pies to figure out the best setup with the PizzaBarrel. I'd like to buy a 21" pizza stone and cut off the back of it (to match the grill rack) so my pizza stone doesn't move around inside the stove.
Very cool to stumble across someone else with nearly the exact same setup and idea. The 55g drums work beautifully!
Cheers,
Matt