Well I looked up on the internet and a stock 455olds which is what mine is requires a 500cfm to a 650cfm so I thought it would be ok, ....but is there any problom with useing a edelbroke carb?? 
Not really, but where's the other one?
Edelbrocks are, for lack of a better description, old Carter AFB and AFS designs. VERY different than the Holley in how it's tuned and worked with. Used to prefer them over the Holleys on street cars back in the day, because they can be tuned quite handily and even in a parking space at a "street meet"....
.....They came quite often stock on dual quad offerings from GM, Ford and Chrysler back in the 60's.
You're problem is you're internet "requirement" is probably assuming daily street use from idle, many partial throttle situations and very RARE full throttle use. On a jet boat, complete opposite. You're going to be running the boat, idling out of the NWZ, cruising, at 3000-3500 rpm, and (hopefully) 5000 rpm at WOT far more often. There really only needs to be four throttle positions, idle, 1/2, 3/4 and WOT on these things........
.........but seen them work very well on jet boats!
The carb brand isn't the issue, it's the CFM. At 600, unless theres a second one on a dual quad or tunnel ram, blower, etc, you're leaving a LOT on the table at WOT, IMHO.
Then again, as BP said, "If it's free I'd run it!". At least for now and look for something a lot bigger, like an 800, 850 or a second 600 and dual quad intake....
Ray
