I apologize for this late reply. You have a beautiful car with good engine components. Having the car mark your driveway every time you drive it isn't going to work. I disagree with many of the replies as this isn't a junk car that you're trying to "poor boy" some extra life out of. My thoughts are as follows:
Don't fill the engine with extra heavy oil, as this will cause an oil drain-back issue with the oil in the valve covers not making it to the oil pan in time. Same with using less than 5 quarts of oil in the oil pan. Both lead to spinning rod bearings.
You're likely going to need to disassemble this engine to fix the issues. Look for worn valve guides, as most machine shops assemble the heads to verify all of the components are returned. I've generally seen dry valve guides filled with metal filings than need to be cleaned out prior to assembly. Also, while you take the engine apart "plastigage" the main and rod bearings. Tight is good, loose clearances cause windage losses and lower the operating oil pan level. Verify the ring gap and verify that the piston ring grooves are perpendicular to the side of the piston. If the ring grooves are trapezoidal, even a little, then the rings won't seal. Piston wall finish, if the bores weren't torque plate honed, then they won't be round when the heads are torqued. Without this process you will likely see oil consumption of 1 qt per 1000 miles, probably not a big deal. While you have the engine apart, verify that the pistons go even to the top of the block, (the factory machining is 0.030" down on one end with 0.070" one the opposite end). If so, have the engine deck machined to a 0.000" piston/block deck height. It's not an oil consumption issue, but an extra power/torque issue. Also, if you want, verify or change the cam to sightly less duration with a 106 degree lobe separate angle. This will add low end torque without losing anything on top.
Best of luck, if you need or want a means of calculating dynamic compression, let me know, I have an Excell spreadsheet that I made years ago.