Just noticed your sig. Keeping RBPs poses a couple of problems, when they get big there are lots of leftover food particles, normally with other type fish you can have tankmates that will consume these leftovers. So all this uneaten food will soon turn to ammonia, to avoid having a spike you will need to provide large areas for benefical bacteria to colonize. Best option would be a wet/dry sump, you can get hang on back overflows so drilling is not needed.
When I had my 65g RBP tank, it was filtered with just a penguin 350, I soon found that was inadiquate and added a wet/dry sump. If you don't want a sump, I would go with a rena xp3 or a eheim 2217, with the rena you have to upgrade the bio media, so either filter will end up costing you about the same. I would also add a Aquaclear 110 for mechanial filtration(the best IMO) and rinse the sponge in this filter on a weekly basis.
The magnum you mentioned is not very good for biological filtration, it is decent for mechanical filtration but not as convenient to clean as a hang on back filter.