The only parts of the valve train that will cause excessive oil consumption are valve seals / guides. Valve seals can usually be changed with heads on the engine but I don't know the specifics of your engine.

There is a chance that oil is pooling at the back of the head, I'm not sure how large the drain back passages are.

I would not put a fresh valve grind on such a high mile motor. When you get good valve sealing, intake manifold vacuum goes up and so does oil consumption. And, . .with better sealing comes more power, that tends to get used . . . stressing high mile connecting rod bearings leads to failure.

There is also a chance that a piston ring has cracked or in extreme cases a piston. I'd do a leak down and compare it to other cylinders. A compression test won't give you a definitive answer.