The answer is that I did end up saving significant money by doing my own labor.

I was rather profligate in replacing parts that potentially could have been reworked and reused for less money such as cylinders, camshaft and some of the engine parts.  Using all new cylinders is equivalent to a factory overhaul these days, but if your cylinders can be reworked you can save a considerable amount of money.  I sprang for some new parts and traded money for time where the parts could have been cleaned up and reused.  For example, my pushrod tubes were corroded and some were chafed by the tensioning springs.  I could have cleaned up and reused many of them, but I just replaced them all for $142.

By comparison, a factory remanufactured O-470-K engine at $300 over invoice from Air Power Inc. (Van Bortel Aircraft) comes to $17,751 after core exchange.  Factoring out the various costs, if I had gone for a factory engine the price would have been:

I discounted $800 from my accessory overhaul cost to account for the price of the overhauled carburetor, which is included with the factory engine.  The remainder of the overhauled accessories are not included with a factory engine.  I also took the IA consulting down to 10 hours since there's less time during assembly but still time needed for installation and inspection.  I have not included shipping because I have no idea what it costs for an engine, but it is probably in the few hundred dollar range.

Neither price includes new engine mount rubber vibration isolators, which is an item that normally would be replaced during an overhaul.  I didn't replace mine during the overhaul because I had already replaced them just a few months before due to age.

On net, I got exactly the engine I wanted and had a lot of fun with my overhaul, vs. getting a stock engine (but bench-tested and warranty-covered) from Continental.