mp 406 crate

I have no exhaust on the car at the moment, and noticed the oil in both the collectors, so dropped a header out and there is a coating of oil on the bowl side of the exhaust valves, if I had oilly plugs I could understand it,, so leads me to think there is no issue with rings and inlet valves, I bought the engine knowing about an issue with oil , but I needed to see for myself, the motor has been stripped twice by two engine companys who could not find anything wrong with it ,I think they may have missed somthing, maybe cam lift, it ows the previous owner a fortune, im wondering if the stem seals are filling with oil and its being sqeezed, there is no visable smoke at the moment,, I took a look at the bearings , and they are like new, all the honeing marks are still present on the bores, and runs and is very responsive, I best do a comp test and maybe have the springs off