I've been checking the vids on you tube and they have a really unique sound especially at idle, they should have awesome performance at full noise! The only restriction is the jet needle, no butterflies, chockes, venturies or shafts in the way.
I'm going for the side draught type with horizontal fuel bowls. Your spot on the down draughts need a big angle to get them sitting correctly approx 50deg angle. I'll custom make a manifold that shouldn't be too hard.