smoker design troubles

[zeroluck]

So I'm new to smoking, but have always enjoyed grilling. I've read lots of forums, posts, websites about cheap offset, and the expensive offsets, enough to know I don't want to go cheap. Recently I've given more thoughts to build your own smokers using 55 gallon steel barrels. Kind of freaks me out though cause I can't find a good source locally (zip 48313) that I trust. The fact that these old barrels could contain heavy metals, oils is kind of scary don't want to get sick saving money. I'm getting off subject from my main question which is I read a build guide for a smoker drew my own up in "google sketchup" and I read the article one last time, and it said it's not a charcoal smoker, but a wood burning smoker. I would really appreciate someone taking a look at my design and telling me why charcoal would not be ideal? Any other suggestions would be greatly appreciated. The pig head is for looks, and is NOT an offset. 
http://www.flickr.com/photos/26198859@N07/6819783016/" target="_blank
http://www.flickr.com/photos/26198859@N07/6819783268/" target="_blank 
I know posting links is discouraged for new poster but you can't see what I'm talking about without seeing a picture. My apologies if I broke a rule

[FR8 Train]

Cool design. I see no reason why you couldn't use charcoal, or lump charcoal with that design. Should work fine. I've seen many pits designed roughly the same way.

[zeroluck]

Cool design. I see no reason why you couldn't use charcoal, or lump charcoal with that design. Should work fine. I've seen many pits designed roughly the same way.

I saw a smoker calculator on another post I think where I'm going wrong is the stack between the heat, and cook chamber I think I'll need to increase it's size almost 9 times according to the calculator. Also Says heat chamber should be 1/3 the size of the cook chamber. I'm at a 2:1 ratio do you think that will be a problem?

[BluDawg]

I like the design I see no reason you can't use charcoal Wood IMO is more efficient.

[HarvestMoon]

I like the design I see no reason you can't use charcoal Wood IMO is more efficient.

Also wood would have less ash.

[zeroluck]

I like the design I see no reason you can't use charcoal Wood IMO is more efficient.

Also wood would have less ash.

I was going the charcoal route because I thought I read up that wood puts out more creosote for the first half hour of the burn.