Thanks to the more experienced folks for chiming in. I had oil pooling on top of the motor + a code for a bad knock sensor, at ~150K miles on my car. Both were cracked. I assumed their replacement was a given while the intake was off, at least on any motor with 100K+ miles. But maybe that was just my car.
And I didn't know about the IRIS O-ring at all! Oh well, maybe next SVX.