Not sure about exactly how you are looking to modify it, but I LOVE the Reef Octopus HOB skimmers. I have never run a sump, so I have only experience with HOB.
I have the BH2000 on my 55, and BH1000 on my 29gal. I had previously used Aqua-C remora skimmers (nano and pro) which worked decent, and a couple other HOB skimmers that were horrible. At one point I had a Tunze 9002 on the 29, but the Reef Octo pulls way more gunk.
Sorry I don't currently have one for sale, but I would look for one of those if you can get a good deal.