Hello chemistcarl !
You can use an external exif editor to set exposure data in JPEGs, and use these tagged JPEGs in Autopano Pro.
Autopano Pro will use these exposure informations (ISO, Exposure Time and Aperture) to calculate HDRI color correction.
If you do not remember exactly what were this informations, that's not really a problem. What matters is the difference of exposure between different shots, that must be right for the HDRI mode.
Anyway, if you do not have these data, you still can use standard color correction, that give great results in most ie. if exposure differences between shots is not extreme (just take care of channels histograms to keep all the dynamic range