A further update, for all those who might care. While I had got the car started, it obviously wasn't right. I ended up pulling the transmission out and correcting the flywheel installation, and also pulling the crank pulley to verify the timing mark on the crank belt gear. What I found was extraordinary: The car originally had AC, so had the dual-sheave pulley at the cam belt end of the crank. A PO had at some point disassembled the two halves of the pulley (necessary to remove it with the engine in-situ), but had misaligned the two pieces when reassembling, forcing one of the studs into place. As a result, the timing mark on the pulley was 60° off! When I had reassembled the engine when it was out of the car, I had set the timing based on piston and cam gear position, and hadn't noticed the crank mark being off. When I later tried to use it, I was making it worse with every change! Anyway, now properly timed, starts instantly, and all I need to do is to fix the off-idle stumble and pre-ignition under load.