2 barrel with stock exhaust??

I think the 'Super Six exhaust' is a myth. My 79 Volare wagon came with the super six slant and the exhaust manifold and exhaust pipes were small, definitely nothing like 2 1/4. I ground out the exhaust manifold to 2 1/4 myself and welded up my own 2 1/4 exhaust all the way back. It made a difference you could feel and I would do it again on my next wagon.
To the OP, You should give the car a good tune-up, adjust the valves, set the timing, etc and then see where you stand with things. If it runs to your liking, great, if not you should be able to switch to a two barrel setup easy enough.