I've found a couple of Lokar shifters for the 727 at Summit Racing and Jegs or just contact Lokar on their websirte.
I'm not at the tail light stage but in keeping with the frenched look I have up front, they will be frenched into the rear panel. Mounting holes in the stake pocket and bed side for wires and mounting have all been filled along with the holes for side reflectors, tie down hooks and the kerosine roadside flares that unfortunately were too rusted to be of any use. License plate will most likely be frenched in as well. My dash panel has been removed for a handbuilt unit and will be replacing the gauges with a modern Quad gauge and speedometer.
318 will fit as will the 392 but bear in mind, neither is a bolt in and can be a daunting task if you've never done this before. It's extremely easy to lose interest in a build with these kind of compexities.