Jase. If the truth be known, the motor may not have been apart for a long time. If this is the case, a good dose of carbon in the combustion chambers is to be expected, we are talking an old design and components which don't have the performance expectations of modern engine development.
For starters, give the head a good deep clean, reassemble and try a leak test on the valves and seats, they may look crap but actually seal OK. You can lap them, but be careful as the seats are narrow. If a valve itself is pitted, it can be refaced. If you change the valve for new, then a change of guide and recut of the seat by your engine reconditioner gives you the best outcome.
Another spare head is a possible, but as usual, may be as bad or worse than the one you have.
With burning oil, sources are the guides and bore/pistons. If it was running reasonably well, no knocks or clanks, a good clean up should do for now.
Piston rings are easy to check, as long as the ring gap is within limits, that's fine. More important is the up and down movement of rings in the piston grooves. There should be minimal up and down movement, if any. You may find the compression rings worn to a T section, so compare the inner depth of the ring with the outer. New rings will do in old pistons, as long as the piston grooves will only allow up and down ring movement within the specified limits.
So all is not lost, it's just a matter of how far and expensive you want it to be.
Surprisingly, just cleaning up worn components will produce almost a good results as new parts. Pistons with carboned up oil drain holes and stuck rings are a typical example.
Swarfy.
