Thanks so much Jay. You know your stuffSweet jacket!
Nothing wrong with replacing that lining. Just be sure and carefully save the label for re attachment.
For cleaning / conditioning, if it is musty or dirty you can clean it with Lexol PH leather cleaner. This will also soften it a bit. after dry, you can follow up with Renapur leather balm. I have heard that Lexol can cause corrosion on metal parts but I have had no problems. I would avoid getting it on the metal just in case.
Lexol is the consistency of shampoo. The process is to put some on a wet rag, lather up a small section, then immediately wipe clean with a wet rinse rag and pat dry with a dry towel. Work a small section at a time. Try to limit the amount of time that the leather is wet. Keep in mind that when you clean the leather, you are washing away oils and conditioners that may have been on the jacket. For this reason I always follow up with a conditioner, either a very light coat, or a heavier coat if the leather is dry. Wait an hour or so to apply conditioner so you don't lock in any moisture.
If a jacket is so dry it is cracking, don't use this process! I have a special process I use to deal with those types of situations.
I have tried many products and this is the best process I have found in the 10+ years I have been refurbishing jackets.
Best Regards,
Jay