Gene, I checked something for you that might give you a good compromise for the tape-hiss. I did not work with it, just did a very fast check, but audicity (normally I don't use it) hass a plugin to use against tapehiss. It is very simple, not much settings, but what you do is take a piece of hiss only, make a profile from that and then preview it and determine the amount you want to filter. Worth trying maybe. Maybe there is so much hiss you will get a lot of aliasing, then try to find a compromise of reducing hiss while still preserving an acceptable quality of the audiofile. I know, there are obviously better plugins, I am sure of that, but for a freebie and a fast check it might be worth it.

I'll be back...