I've got an 83 with a 350 and I'm running Hooker block hugger style on mine. I've got a 3" lift on my drivetrain but I believe they'll work fine on a "stock" set up.
Sorry I can't recommend a muffler - I'm running Moroso's but they're just a bit much on the road. Something with a deep, mellow tone and not so much bark would probably sound pretty good.
Remember that you have limited space under there for too much of a muffler so take some measurements and see what's available.