Can FLIR`s OEM cameras accept an external sync from the PCI-1422 to command the camera to digitize imagery at 30 frames per second?

No. External sync is only available via the 30-pin SAMTEC connector, which is (was) the primary electrical interface to the legacy Photon camera. This connector is also furnished by the Photon Replicator Board, which is an optional accessory for Tau2 cameras. The Serial-In, Parallel Out (SIPO) module -- typically used in conjunction with the PCI-1422 frame grabber -- passes digital data exclusively.

This question and answer also applies to the legacy Photon camera models. The Photon product line and its accessories have been discontinued. The information here is provided for historical reference.