Tom, HP4, HP5, HP5+ and Pan 400 have similar development times.
I would suggest to waste a few sheets to get your personal EI and development times. Also for a film which is this old probably trial and error is the only way to go.
A developer for expired film:
On the other hand if you want to try your new camera, doing so with fresh film might be a better idea. Freestyle sells Arista.EDU Ultra 4x5" also in boxes of 25 sheets at a reasonable price. Many people like that film (re-branded Fomapan 100) and it is much easier to achieve better results in a shorter time this way.
Last edited by Aron; 10-30-2009 at 04:31 AM. Click to view previous post history.
Reason: adding more advice