Corbin,
I made my own handle bar (see it at post your homemade handlebars here!) based on your information but I used different tubes as I guess there were big difference in diameter with your design and thinnest tube was the one with highest stress.
My order to Aircraft Spruce (enough to built 3 handle bars) :
1.00 of 03-05400-2 4130 STEEL TUBE 7/8X.049 2FT
1.00 of 03-06200-2 4130 STEEL TUBE 1X.049 2FT
1.00 of 03-07100-3 4130 STEEL TUBE 1-1/8X.058 3FT
1.00 of 03-07810-1 4130 STEEL TUBE 1-1/4X.083 1FT