Whats the best way to get this fitting off

I used a old rusty impact socket that I had to grind slightly to fit hammer tap in tight inside and welded it on. Then while still hot PB Bustered the crap out of it for two days. Clamped the manifold in the 20 ton shop press and used an 1/2 impact on low and hammered on it for a bit both loosen and tightening. Did not hurry.