The Marlin sounds ideal for your current hunting situation, so I'd start with that, if it was me. I once sold off a Marlin 444 to get the money for a bolt action 30-06, and I've been regretting it ever since. Get the lever gun, put a good peep sight on it, and save your money for a bolt gun later on.
Thank you for all that you and your co-workers in the Coast Guard do every day. I've been over the Columbia River bar enough to understand just how valuable you folks are, and I've got relatives fishing off Alaska's coast. You guys take on the biggest national threat of all, mother nature (and human nature is a close second)! If you're ever stationed at the mouth of the Columbia, a 45-70 will make a dandy hunting rifle around these parts, too.