Not sure if you ever sorted this.
pf or picofarads is for setting capacitance for MM or MI carts.
For moving coil you want impedance or resistance measured in ohms.
I scanned through the manual for the C1 and those switches are only for phono 1 - moving magnet/moving iron. The manual states phono 2 is 39 ohms. 39 ohms is way off from 300 and is
I'm not familiar with Carver stuff, my Jolida has 70, 100, 150, 300, 1,000 and 47,000 ohm settings. The manual states the gain can be altered by replacing resistors, but again makes no mention if the resistance can be changed on phono 2. I'm sure somewhere inside it could be changes, but that may be hard to find/figure out.
You could use a step up transformer (SUT) into phono 1. Or a MC pre into one of the other inputs.