Is there a nice and easy swap you can do for this? I prefer a non sunroof body style but that comes with some compromises in regards to the brakes, among other things I would want to change.

 

If you stick to the later (81+) FB chassis, then swapping in a diff off a GSL (came with discs) is a bolt-in swap. Easy-Peasy. Later 84-85 axles will also swap. These are beefier, at least for the -SE model. Believe the late 12A's axle is the same as early FB...
If you are after an earlier SA (78-80) chassis, then all you require is an adapter brake hose that goes btw the body brake hard line and the axle brake line. The thread pitch was changed in '81+. Racing Beat used to sell these, as does (did?) Mazdatrix. Other than that, a drop-and-swap.

Stu A
80GS w FB rear disc axle
AZ

 

yes the 84-85 12a/13b cars have larger axle. cars before have small axle. not quite sure if the same is true for the front spindles or if it's just the SE that had the different spindles due to the larger rotors. now a full SE suspension swap would do all that and give u better wheel options due to the 4x114.3 lug pattern.

 

All '84 - '85 RX7's have the same front spindles / strut tube. The rotors/hubs are different between the larger GSL-SE and the regular GS/GSL, but they all use the same bearings on the same spindles. The earlier cars had narrower spindles with smaller bearings, but I'm not sure if that changed in '81 or '84.

 

There's an 83 gsl shell a couple hours away I've been thinking about purchasing. Its missing a hood and left headlight housing along with the whole drivetrain. So maybe worth while to swap a bunch of stuff right away before putting it back together. So to get to my question would I need to swap out the lug pattern for the front/rear spindle/axle?