I assume you checked the ring gaps on assembly? Those specs sound about right for the 235 bore size. Total Seal rings have a habit of being rough on cylinder walls if they're run on a street engine for extended mileage, resulting in barrel-shaped cylinders with more wear in the middle than at the top. That's why I don't run them on the street. The low-mileage race engines never get a chance to run long enough for much cylinder wear, something usually tears up long before we wear out the cylinders.
I'd look at valve guide seals first. It's been long enough since I was into a 235 that I don't remember what the stock guide seal setup is, but on most of my street engines, I use the umbrella-type seals that ride the valve stems and deflect oil from the top of the guide. If yo use that type, don't use the o-ring and sheet metal deflector that is the usual type of assembly found on Chevy from the factory. It's possible to run the valve guide too dry, resulting in rapid wear of the guide. A tiny bit of oil should be allowed to run down the guide to keep it lubed. "Positive" valve seals, the ones that clamp on top of the guide with a spring, also have a habit of starving the guide of lubrication. I only use them if there's a clearance problem with multiple valve springs.
It's possible for oil to be lost down the exhaust guide, and be burned by the exhaust system, and never show up as fouled spark plugs. Be sure to check both intake and exhaust for correct stem-to-guide clearance, and correct guide sealing.
BTW, what weight oil are you using? Also, what about piston skirt clearance, and cylinder finish when the pistons were fitted? Cast pistons on that engine should have been fitted with about .0025" clearance, somewhat tighter if you're using hypereutectic pistons, which don't expand as much when they reach runnung temperature.
Jerry
