Subminiature film: Panchro Crystar (Film Speed?)

Just put a roll of Panchro Crystar 17.5mm film into a Bell 14 subminiature camera.

Unfortunately, the film package says "Fine Grain High Speed", but nothing more.

Since the shutter speed of the Bell 14 is fixed at 1/50 (quite a bit of light), I'd like to get as close as I can to knowing the film speed. If this was a standard sized camera, I'd guess ASA400 and go from there. But from what I've seen, does ASA400 speed film even exist in "subminiature land"?

Thanks in advance.

Certainly it does in the context of modern films for Minox, etc. beyond what people split and loaded themselves. Agfapan 400 was available.

But given the age of the film (50s, maybe early 60s), I would think "high speed" means iso 100. Then factor in whatever you feel appropriate for deterioration of film speed. I would expose at iso 50.

Thanks mgb. Yeah, I had a feeling from what I've seen that the older sub-mini films seem to top out at 100. Will also take your tip and shoot it as iso 50. The packaging looks no later than 60s. Thanks once again!