thats normal then, if its full and over flowing thats a head gasket, or if its empty its a head gasket.
you can also when its warmed up some, rad cap off, rev the engine watch the rad for bubbles. if you see bubbles the head gasket is bad.
then theres the good old co test for the rad, it will tell you if exhaust gas is in the engine's coolant. aka blown head gasket. not a cheap test kit to buy. around 60 bucks or so iirc.
being you got oil on the plugs, (not coolant) and low compression. still looks like bad rings.
