I have a model I call an East Coast Gun. It's not a full on gun, but it's a bit more big-wave oriented than a step-up, without compromising performance. Designed specifically for the biggest surf we get in NJ. My personal one is 7'0, but I'm a bigger/older guy. Handles DOH with ease. Key design features that set it apart from a typical step-up are bottom contours and rocker. Depending on your size/age/ability and where you plan to ride it, you can go down to about 6'6 with this design, on up to about 7'6. Below that just ride a step up or basic rounded pin hpsb, and over that you need a more gunny design. PM me if you want more details.
Got a 7'4" for sale at Lightly Salted good for places where there is a lot of water moving around and during hurricane season or big winter swells. Board is EPS. Make me an offer that's reasonable. Asking $350
I just picked up a used Roberts Black Thumb but its not really a step up for me, just a board for when its good. Same dimensions as my shortboard just with a pulled in round tail and different rocker/bottom contours. I was looking into getting a step up but I couldn't really justify spending the money on something that I probably won't ride very often. I went with the Black Thumb because its more versatile and should still be able to handle any big swells we get in NJ.