LA or poly

I'm sure this has been asked before but I don't know the answer so I will ask anyway. What is the difference between a LA and poly engine? I hear these references to the 318 engines and am just curious. Is one type better than the other? Is one worth more than the other? I know someone who says they have a 318 for $150. Don't know which type it is. I have a 63 A body with a /6 and if I wanted to swap to a 318, would the type of 318 matter?
Author: admin