Sorry about that Scott, don't know where i got John from. Yes the IV bags are the way to go in my opinion. The real IV bags need to be changed out every year but the bags made for Zipp Kits seems to last twice as long. I have one in a Crackerbox that is three years old which I am changing this week but it is still going strong. I change out the ones in my Outrigger, Jersey Skiff, Thunderboat, F1 Tunnel, & Cat every year at the beginning of the season. You can buy their bags completely rigged (bag, fuel line & fuel T installed) for $12 and then just get replacement bags for $5 when needed.
Are you going to use a clutch? If not then you don't need a water pump. A good double water pick-up rudder will supply enough water to cool a modified 29.5 or you could use a single pick-up rudder and add a "blast pick-up". In any event with your pipe running internally I would definitely use two water feeds. One for the head and one for the pipe flange/header.