To follow up and answer my own question, some additional web searching suggested simply unscrewing things, so I tried it and it worked.
Grasp the front of the the lens (ahead of the aperture ring) in one hand, the base in the other, and twist. It's a standard right-hand thread. The entire optical assembly unscrews from the focusing assembly. Be careful not to lose any internal shims when you remove the optical block, my lens had two of them. Also, note the orientation of the optical block to the focusing base for reassembly.
With the optical block out the rear group can be unscrewed, again standard right-hand threads. This was all I needed to be able to blow out the dust. Reassembly is the reverse, as they say. Total elapsed time was under 5 minutes, not including nearly an hour of searching and watching YouTube videos of the Type 1 and Type 2 lenses