I had this problem some time ago on a Cleveland block I was stripping. Some filter adapters have a thin hex while others are round as you mentioned. Even lathing the socket flat to remove the chamfer didn't work- it was so tight my effort stripped the hex corners off. So I took a piece of square stock CRS, drilled a hole in it and threaded the hole 3/4-fine SAE to match the filter threads. I lightly screwed the CRS piece onto the oil filter fitting, added a 3/4-fine setscrew that I tightened REALLY tight against the fitting top with a cheater bar, then used a 24" Crescent wrench on my CRS piece. The block fitting gave up and unscrewed.
I think all Ford blocks have these fittings. They are torqued into smoking-hot engine blocks at the factory so when it cools they are very, very tight; half-hearted measures won't budge them. I used a big setscrew as a jam, 'cause they are gr-8 and unlikely to strip while being sufficiently tightened against the filter fitting. A gr-8 bolt probably would have worked just as well.
Once the fitting was out, I found a ledge of hard, gritty oil sludge built up around the filter adapter threads, so if you're reconditioning a block, its a good idea to remove the fitting to clean out ALL the sludge in the part. And if you intend to re- use the block & fitting, red Lock-tite is recommended. If it loosens while the engine is running you could lose the engine.