Does the filter have any markings? I am fairly certain its not a Penguin 200 if it has 2 bio wheels. Older style double wheels are 300 and 330's with the 350 being the most recent one. Even if that's the case that's not going to be enough filtration for a tank full of goldfish. You want to turn over the water A LOT and a 350 will turn over the volume of your tank 5 times an hour on a good day, much less once things start to break in and filter pads are in place. Also, your stocking plan would be overstocked, six gold fish in that size tank is more than most people would recommend. Conservatively you'd be looking at 3, aggressively at 5. Six is doable but it's more vital than ever to really filter the tank.
As much as I love HoBs and Marineland HoBs specifically I just don't see them doing what you need in this case. A canister filter or two is going to be needed to handle that kind of load. I'll leave recommendations on what kind to people more experienced with them than I am.