Dont pay too much attention to there amp ratings.you could 40-50% on top of that once loaded with a prop in the water,as for wattage you wont get no where near 900watts on 3s,to get that sort of watts you need to run them on the voltage limit
here was a post on rc groups some 1 got a data logger on 4074,2200kv leopard rated at 120amps,the data logger showed hitting the throttle the amps would spike over 200amps and was running a conservative prop octura M445
you still need to change them deans connectors on both lipos and esc you might be OK with prop though
I ran a 3674,2200KV on 4s with x442 prop in 25" deep vee hull with no issues but your hull is much bigger in comparison
Heres a vid but dont forget 1 thing when watching it,yours is a bigger hull on lower cells so wont be any near as quick
http://youtu.be/hRn-rHnsVGk