Yep, it looks like it's a 428. I don't think that they were originally offered in the Firebirds but who cares becuase it's a Pontiac big block! As far as plugs, I've tried 'em all and haven't seen a noticable diference in performance. You may as well go with the AC delco 44S and gap them to .035". They are cheaper than most others and do just fine. Also, I've seen torque specs for plugs range from 23 to 25 ft-lbs.