Once you get the carbs dialed in they shouldn't give you any more problems than a 4 brl would. I have a tri power set of Rochester 2G's on my 57 Olds and once they are dialed in there are two things to remember. Keep you foot out of it and don't tend to tinker.

4 brl's under 600 cfm tend to be better at gas misering, but there's no comparision when you get all 6 brl's flowing. You can actually watch your gas guage needle go down if you get into it long enough. Used to be fun when gas was under $2/gal. Not as fun today.