There is also a Stant 'Standard Grade' 205 degree thermostat that should give about 1% MPG boost if a VERY careful test is done.

Stainless steel wire mesh across the ports between two intake gaskets will 'probably' reduce fuel droplet size and slightly improve fuel economy.

Rigging up an exhaust gas recirculation system feeding into the air inlet might be good for 5% better MPG at highway speed, but the idle quality will suffer unless a way is available to turn it off below 1500 rpm.

I would not personally be afraid to try the new Mobil One Synthetic OW-20 oil, but only if the rings are in good shape.