Ted, I've had preset lenses (what a pain!), and they work fine with the Spotmatic's metering. Just stop it down to the taking aperture with the freely-moving ring, turn on the meter with the slide switch on the mirror box, and you're in like normal. 🙂 Easier to use it in "aperture priority" mode, centering the meter by changing the shutter speed, but it's possible to stop down a bit more by moving the freely-moving ring (just put a little muscle on it), and open a bit by moving the click-stop ring. The only thing that doesn't work as usual is that pushing up the meter switch doesn't stop the lens down automatically at the same time.
One of mine was a Spiratone 105mm f/2.5... Not too bad, especially for the price, and its interchangeable mount meant I could make it fit the new Pentax H3 that replaced my Petriflex V that I originally got it for. I've also had several Auto-Takumar lenses, including the 85mm, which actually have a semi-auto diaphragm -- It stops down automatically when you snap the shutter, but you have to crank it back open manually afterward. I have a couple of 55mm lenses now that are like that, but no presets any more.