During the leakdown test, you should be able to hear air coming through oil fill cap. That will tell you if the rings are bad. Air sounds through throttle body is intake valve seal. I'm not sure how you determined that the valve seals are good. Typically that is a oil smoke on startup that goes away once warmed up. I had oil burning on my 94 1.8L. The rings were stuck in the piston and behind the rings are little pressure relief holes that are supposed to help push the rings against the bores. All of that was plugged up. My engine had 250k miles and still had good cross hatch. I just cleaned up the pistons, bought stock size rings and bearings and put it back together. I also purchased a ball hone and deglazed the bores to provide a fresh surface for the rings. The parts were very cheap but it was a lot of work. I also splurged and had the cylinder head rebuilt. Engine runs great for last 40K miles. The ring, bearing, and gasket kit is really cheap but when you add in maintenance items like cam belt, tensioner, water pump, hoses, etc. It can add up but you still end up with something ready for another 100k miles and you have a lot of experience with the car. A Chilton manual supplies enough information to do the rebuild. If you have the time, patience and tools, it's a fun job.