Jet the red pipe pretty close to the B-Pipe. You will need some adjustments on the low and high needle and maybe a slight change on the low jet, but should put you fairly close depending on other mods. As far as the water routing goes, do you have single or dual cooling from the pump and is both of the spots on the Riva Manifold taped for cooling lines. I found a link to the routing a while back and will have to find it again, but it will help knowing your cooling setup.
Kurtis