Just wanted to report that I got the cutting edge cut down this afternoon. I used an .045" cutoff disk in my 4.5" grinder, and it worked great. I had managed to get a nice straight groove across before the Sawzall blade pooped out, and I just kept making passes back and forth as it went down. As the blade got way down in the cut, it started to get grabby and hard to hold steady. I had the handle screwed onto the right side, I guess because I'm left-handed. I switched the handle to the left side and that made it easy to control, all the way through, untill the end flopped off. Then I switched to a regular grinding wheel and took the sharp edges off. Didn't take long at all. I set it on a couple of sawhorses outside the garage, and with a stiff breeze I didn't need a mask. Used goggles, though. Those sparks are rough on the eyeglasses. I compared the used disk to an unused one, and it had only lost 1/8" of it's diameter. It was a number 27 disk. Still don't know what the difference is between type 1 and type 27. They're both metal cutting blades.
Thanks again to everybody that responded with suggestions, you guys are great!
