Is this frame design possible?
 

I like the looks of the Columbus Zona steel triangular shaped tubes. Is it possible to weld a Reynolds 853 triangle on those tubes. I was thinking it would be awsome to have a semi aero top tube mated to traditional round Reynolds 853 seat tube and Reynolds 531 curly stays. Can anybody picture how unique it would look?

I don't know the tubes you are talking about, but I would imagine you should be able to join tubes through a round seat post. A triangular top tube sounds a little uncomfortable...