1980. Straight pipes to Magnaflow mufflers at rear.  Sounds great, but the stink is intolerable.  Backing it into the garage is 24 hours of exhaust stink.  I drove the car for an hour with the t-tops off and I had to stop.  The fumes are not coming into the cabin through the floor (no holes) but just out the pipes.  What do I need to add to the system?  Cats?

I would pull a spark plug out first and see if it has a lot of carbon or soot on it. Your carb might be running rich. If it's a nice light tan color then I would say the carb is fine and put a couple free flow cats on it.