Doubtful that they'll work in any dedicated TTL mode directly, mounted in the shoe. If you're using print film, it won't be such an issue, but with transparency it may be.
Interestingly, I discovered my Pentax 645N will work with my Nikon-shoe'd Yongnuo flash triggers--and the wakeup feature works with my Nikon SB800s. Not in TTL auto and radio wireless both, but it's a neat feature for wildlife remotes at night.
Also discovered I can also use my Pentax 200T (or almost any Pentax analog and most digital TTL dedicated flash in the shoe or on a bracket with a dedicated TTL cord), and with the flash set to TTL, also use a couple of Nikon SB800s remotely in Optical TTL mode. The Pentax 645 has true/realtime Off-The-Film sensor flash metering to measure the light and quench the flashes --even the optically triggered and quenched Nikon ones--when enough light has built up on the film. Most other modern and all digital cameras have TTL that is preflashed-- and measured by the metering cells in the prism before the mirror swings up and these generally won't work with common optical slaves/triggers. But not the Pentax 645/645N (nor the LX, nor the PZ-1). Pentax film era gear thus offers a lot of flexibility with optical flash triggers.
The key to doing this is to set the remote flashes close enough to the subject that they're not overpowering the subject before they can be quenched. Kinda goofy, but works great (Goofier still is that the dedicated Pentax AF500FTZ flashes of the era don't have optical TTL quench, though they do have optical triggers built in.)
Too, the 645s will work with most of the dedicated Pentax TTL flashes going back decades. These often sell for cheap because the analog ones like the 280T and 200T don't work in TTL with recent cameras that preflash. I've bought any number of old perfectly working ones for $20-40.