I recently purchased and 83 z28 camaro and now I wish to replace the factory seats with some racing seats and possibly add a 4 point seat belt harness, however I was wondering if a new 4 point harness would work without installing a roll cage. Or would a new racing 3point seatbelt be better?

 

someone does make a harness bar that bolts into the rear seat mounts and the shock tower bolts. i do not know who makes it, but they are around. take a look around, or see if you can make one