Recording from cassette

I have volunteered to re-record some dialog that was originally, recorded in the Vietnam War era, into a digital format, the quality of what I have heard so far is OK, but there are newer recordings dubbed into the beginning of the tape, I noticed last night when I started the project, that the original recording levels change from one dub to another, considering the last dub was done in 1989 this is not surprising. Is there a way to set up Audacity to emulate an auto-level type of function, in real time during my recording of the project?

No, you would need an external limiter in order to do that. If the input is going to clip, there is nothing Audacity could ever do to help that, since Audacity won’t see any audio until after it’s already been clipped. At that point, the damage is done already.

It is technically possible for Audacity to auto-adjust the gain on the soundcard if it begins to clip, but since there will be a finite delay before that can happen, it can never be perfect. However, this feature hasn’t been written (I have no idea if it’s planned either).

The best thing to do is monitor the recording, keeping the gain as high as possible for each segment. If it begins to clip, rewind and have another go at the section again.

If the tape is fragile and you’re worried about how many times you’ll be able to play it (tapes don’t last forever as I’m sure you’re aware). Then it’s ok to be very conservative with your gain setting. Make sure you’re recording at 32-bit samples though, that will give you more resolution and, therefore, better results if you have to amplify everything afterwards.

Update, I managed to get about 0:50 of audio recorded, the level was ok a couple of real brief clips, nothing to bother anything, but I do have to comment on the quality of the tapes, they are Certron branded. After 0:50 the audio dropped, I stopped the recording process to see if there was any more audio on this side, none detected, just normal noise, then I tried to fast forward and the tape drug bad, I managed to get to the end of side A and flipped the tape over to start on side B no FF but it does play no noticeable drag.
I have an older (do they still make high quality decks?)full logic control, definitely a soft touch tape wise, I an sorry this project came to me so late in the game.
Regards Ryan