I decided to take another stab at removing the bearings from a used crankcase before I start using the new one I just installed bearings in. I have an electric hotplate, so I tried that approach this time, and it finally worked. I had to get the crankcase so hot that the oil all burned black, and my IR thermometer wouldn't tell me how hot it was, but the bearings finally came loose. I was able to whack-out the rear bearing, but the front bearing required grabbing the inner race with a pair of needlenose pliers and pulling it out. Unlike larger engines, the Picco P-0's crankshaft is the full diameter all the way through the crankcase, so there's no way to press against the inner race of the front bearing from the back side -- pulling is the only way to get it out. Once I gave up, cranked the hotplate to maximum heat, and let the crankcase sit on it for a full ten minutes, the front bearing finally came loose.

Bah. What a shitshow. At least it worked this time.