While obviously not a brilliant piece of engineering, I think the Xfire gets a little bit of a bad rap. I ran it for a couple years before going up to the LS and it was fine, zero troubles and it got decent street mpg (low 20s was the best I got when optimized). It's a good point that in a boat application where the engine is going to be running at a constant high throttle, a tuned carb would do just as well on fuel consumption.
If you want to go carb, I have a brand new Holly 750 (vacuum) with quick fuel meter blocks I got for the snake. That's still gonna be a little while and I want to go TBI when the time comes anyway, so it's available if you want. Though maybe a 750 is too much carb for that cam.
