Poly Engine what was good/bad about it and why is the LA better?

The LA was better for Chrysler, because it cost less in production. The poly engines arguably have better potential in their heads. They just never really caught on. The LA was smaller, lighter and cost much less for Chrysler to make. The cars were getting smaller and less and less room was available for such a wide engine. While the blocks are identical in terms of shape and size, the heads made the 318A engine much wider and with all of the little A bodies in the early and mid 60s, Chrysler needed something different, so the LA was born. The polysphere engine had a great run though, all through the 50s all the way to 66. They were great engines, all of them. Dodge, Chrysler, Plymouth and Desoto all made their own versions of polys for many years. They wouldn't have wasted time on a POS design.