DoubleV said:W30 is a 455, so no, it's not a 'W30 block'. It seems it is just a standard 71 Olds 350. They didn't have any special/performance versions in 71. It's a very good platform but there is a very important issue about them and it applies to you; they have low CR from the factory due to large dished pistons. What does this mean to you? Well, first it means that if you took the heads off and replaced the head gaskets with standard Felpros, your already low CR will now be even worse. Secondly, that cam you just bought will be GARBAGE whether you replaced the head gaskets or not. It's just too big of a cam for your application and even if it were the correct size, there are other cams out there that would outperform it anyway.
Put that cam in your engine and you will have a turd. A big fat stinky one.
Thats a good way to just shoot me down completely. I'm not going for a drag car or anything. How is the cam WAY TOO BIG? It's not even that big...I wasn't going for balls to the wall power here. Just a little ole 350.