If you coast down a long hill with the throttle completely closed, and then you stomp on it pretty hard do you see any blue smoke cloud out of the exhaust? If so, it's probably getting lots of oil through the valve stem seals. If you have been cruising at steady throttle for say a couple of miles, then nail it hard full throttle do you see any smoke? If it smokes in that case, it could be oil control rings. If valve guides are really bad, it may smoke some in both cases. Around that 1 quart per 1000 miles is quite a bit of oil consumption.
On that engine, it would probably be pretty easy to replace the valve guide seals. Just need some nylon rope in the cylinder at TDC to keep the valve in place and a valve spring compressor that will work with the heads on.