If I were you I would get two slightly smaller HOB overflows. This will give you redundancy in case one loses siphon or clogs.
Also, do you know what kind of flow rate you want to run? I am setting up a 220
also, with a 55 gal sump. I estimate that this setup will have about 250 gallons of actual water capacity. I want about a 6X turnover rate so I am aiming for about 1,500gph. I drilled my tank with three of the H2Overflows, each rated for 1,200gph. That gives me a total of 3,600gph of flow capability, which is over double my target flow. I think that this is important in case one of the overflows gets clogged somehow. I am using two Rio 20HF pumps, again, for redundancy in case one goes out. They are rated for about 1,200-1,300gph at zero head height. However, at my head height of about 5', they will each flow around 800-900gph. I can use hand valves on the pumps to choke them down in case the flow is too great.
I mention all of this because these are factors that you need to consider with your setup to decide what you want to do.
