Geoff-
I think you are running the Turbo 22R? If so, 325cfm isn't enough to feed a turbo anyhoos. That bad dog has to breath....same thing with the exhaust. I would go up to a 350-4000 cfm carb, and maybe ask around for advice on the jetting. Jets can easily richen up the mixture, and can be changed relatively easily. Kinda trial and error, but easier than constantly looking for a different carb. I don't know if you have an O2 sensor or not on that thing, if you do, you can fine tune it with a Edelbrock tool, which tells you where the mixture is at based of the amount of Hydrocarbons (unburnt fuel), in the exhaust. It's on the pricey side, at about $150, but can make like a helluva lot simpler.
Ryno
Build it like a Rhino, and Leave it be.