I would do a simple test to check for the presence of water in the engine oil. Get the engine completely warmed up or go for a drive, Immediately after returning siphon about 50ml of oil from crankcase and put it in a clear glass container. Let in sit for a while and see if there is a layer of coolant/water forming on the bottom. If there is the problem most likely is with the head gasket.
I also tend to agree with Rob @ NeedsWings and look into doing an engine swap. Looking at the build on the caps and inside the valve cover I would say your problem is not new and the previous owners didn't follow very good maintenance practices.