According to my information, you should have a chrome top air cleaner. The 731 code you mentioned is listed as a "dual stage" H.D. air cleaner. I am not sure if this is dual, as in two intake snorkels (sp?), or if the air filter itself is dual stage.
Your post says your car is an A/C car. My 350 HO is also an A/C car, and my air cleaner is single snorkel. If in fact you need the two snorkel with chrome lid, Quenton is right - they are hard to find and expensive on eBay. I agree with Terry (for a change) - give Ron at Potomac Pontiac Parts a call - 301 668-0101. I was up there not too long ago and he has some air cleaner set ups.
