I like Hagerty, I have them for insurance, and the magazine is incredible. That said, they are not all that Pontiac knowledgeable just like HOT ROD and others are not. Go to a Pontiac specific site and you will find all your information from people that love Pontiacs. I myself always look for the casting numbers that are right next to the distributor hole for my date. I have more than once trashed an unscrupulous seller's claim that he had a 455 when the displacement casting clearly said 350. Check this out. Engine ID. Or this; Engine ID And this: Engine codes Remember that all Pontiac heads will bolt onto all Pontiac blocks so that any combination is possible. Back when they took the lead out of gas and it was worse than cat pee I took 455 heads and put them on a 350. That gave me super low compression that allowed me to use whatever sludge gas was available while also allowing me to use 52° total timing and very rich carb jetting. It as 1950's hot rodding all over again. Count the engine mount holes on the side of the block. Check your head and intake manifold numbers too and let us know what you figure out.