The blocked PCV system could cause the whole problem. Make sure the entire PCV system is totally clear and flowing before doing anything else. I think it is possible to clean the valve cover once it is removed. My first choice of cleaning would be to let solvent from a parts washer (which you probably don't have) circulate through the baffle. Make sure that the hose from the valve cover to the intake pipe is clear because that is where the PCV system begins. Make friends with an engine machine shop. They will want to be your friend as well, seeing that you may need additional engine work and probably know others who may need engine work in the future. If you eventually find you do need to re-ring, less expensive cast iron rings are a better choice than premium rings because they will seal better and quicker with cylinders that are less than perfect.