What's the deal with the Poly 318

In about 1972 my 440 RR with 3.54 gears would run 13.0's

A guy I know had built a "stocker" about a 63 B body with a 2bbl poly. Of course it was not a street car like my RR. So who knows what rear gear, and what had been done to the TF. It ran right with my RR for ET If someone can look up what "then" stock class and the record back then it was alleged to run right on the record for class.