Big Block muffler choice
My idea includes two of these
DC Sports Universal Round Muffler 2.5" Inlet 3" Outlet
DC is a quality brand from the JDM tuner world. It’s straight through, 2.5” ID to 3” OD so you can reverse it.
Run them after the axle, all the way to the bumper if you want to run tips, and weld the tips on the end of the mufflers.