PC-3 is rated 40 henries at 35mA, for use with the S.E.X. amps. It has a tap rated 20 henries at 50mA, which is used with the Stereomour II amp. You can obtain one from Bottlehead replacement parts.
Hammond does not provide enough information (specifically, identify the start and end of the winding, and the winding capacitances) needed to confirm whether it will work well as a plate choke at 8 Kohms.