The vertical as you describe would involve as much or more pipe bending and does the underslung. The exhaust route would be as tortuous as the underslung. The original vertical was the lowest cost to produce and gave a direct route for the exhaust gases. For many purposes, I like the underslung better.
I have not miked the pipe, but some size of EMT ( thinwall conduit) might be close enough to be usable. If so, an electrician could bend it if a good hydraulic bender is available.http://www.republic-conduit.com/Documen ... onduit.pdf
If the sizes do not match, and they probably will not do so, I would use the EMT that is larger than the exhaust. Some welding might be required at the ends.
This might be your Plan B or C.