look its Z 28!

I have an 83 z28 camaro with a 350 swap in it. Its a 5 speed manual transmission and has a posi rear end. The previous owner i bought it from unfortunately drove it like an ***. All the gears are pretty messed up. im having trouble trying to figure out what the specs on the rear end are. any ideas? and what kind of rear end do you suggest i put in? im looking to put a little performance into it.
thanks!