The carb will have to be readjusted for a much richer mixture, and high compression is good for e85, propane, or CNG. There will be some power reduction, but with a high compression engine it will be close to gas.
For the carb, you'll want a higher CFM then stock, the extra fuel will take more volume. Also you want to get new jets. I don't recall if the Weber uses step-up pistons, rods, or whatever, but you may need those too. I think the Webers have a very adjustable idle, so they're good for this kind of change.
I'd go ahead and pick up a wideband O2 sensor kit for tuning, it'll save your investment. The best thing about them is that the sensors are the cheapest part, so you can put them any car you have, or your buddy's car, and really get use out of them.
And definitely, definitely keep the water heated intake, electric element, and exhaust heater. E85 takes a lot more heat out of the intake charge then gasoline.