What is the best knock sensor for my application?

[FattyBoomBatty]

good info. I've heard that a 350 chev. piston is about the same size too. Some guy went to an autoparts store and searched through the list of engine rebuild kits to find a similar bore size GM sensor. I'd almost like to go with a GM sensor since I read it is supposedly more reliable. But if the 3s sensor is not horribly expensive and fits, that might be a better choice.