I asked Profoto if they could find a way to make the B1's work with the Pentax 645z in HSS. Below is their response. If you are interested in HSS with the Profoto B1's, please email them and let them know.
Hey Darryl,
Thanks for reaching out to us. There isn’t a firmware fix that can be done to enable TTL and HSS for the Pentax 645z. A completely new TTL remote would have to be created using the pin structure and TTL codes from the 645z.
That being said Profoto is always looking to expand on it products that pros need to do their job. We make products based on the amount of demand we receive from the photographic world. I will make sure that your request for a Pentax Remote makes it to the product development team.
In the meantime you could always shoot with glass with leaf shutters as this is a huge advantage that medium format cameras have over 35mm dslrs. I’ve done some research and have found that people seem to be having tremendous success with the LS glass from Pentax.
I hope that helped answer your question. Let me know if you have any others.
Thank you for choosing Profoto.
Chris Fain
chris.fain@profoto.com