I have a smoker that is made out of a 275 gal tank. It is reverse flow so the cook chamber is a little smaller, but my firebox is 28" x 28" x 28" so I would agree you need a much larger firebox.
What is the diameter of those smoke stacks? That seems like a lot of exhaust volume. You want to make sure the size of the firebox and smoke stacks are proportionate to each other and the size of your cook chamber so you get a good draft without losing too much heat. Check this out for help: http://www.feldoncentral.com/bbqcalculator.html
As far as Thermometers, the Tel-Tru smoker thermometers are awesome and extremely accurate for a bi-metal thermometer. http://www.teltru.com/s-141-anodized-aluminum-dial.aspx
Edit: Just saw the last two posts. Guess I should have read that first
It would definitely work well as-is for a hog cooker as aawa described. If you want to modify it into a sweet reverse flow pit, you would just have to remove that end stack, seal up the end and open that duct up on that side, plus build a larger firebox. Either way it is a nice piece to have! If you cook a whole hog on that thing you gotta post some pics. Or better yet I'm coming down there to eat some!