The bulb bench tested OK but I found the oil pump shaft seal had popped out of it's place and the lip spring had broken, possibly allowing some/all of the oil to drain into the transmission. The water/transmission oil cocktail had some tinges of purple coating the gears so that could have been 2T from the oil tank, draining it and causing the scoring/seizing rings. Speculation, I know, but there's always something new to learn no matter how long we've been fixing stuff. I'll test the oil level sender when the engine is re-installed and there's electrical power to test it. Thanks for the suggestion.