With roller cams, you don't need a special assembly lube. Most suppliers, including Competition Cams, recommend thoroughly cleaning the lifters with parts cleaner or mineral spirits, then giving them a thorough soaking in motor oil. I usually do that, install the cam, drop the lifters in place, then pour a couple of quarts of oil over the whole mess. Roller lifters do not require a break-in period either. You also need to make sure that the cam is not able to walk in the block. You might want to read this article:

http://www.chevyhiperformance.com/te...8_0307_roller/

Someone else needs to answer the ring questions, although I don't see how plactic on the oil rings could be a good thing.