My jaws are missing also. I suggested to Kevin a long time ago about making them.
I think he said the volume would not be worth the time involved from a business standpoint.
I think that gray-green color got used on machinery back then. The vise got a new coat of paint along with everything else in the shop.
My bear looks looks the same as yours and I had no idea they had gone up in value that much :D
https://www.garagejournal.com/forum/showpost.php?p=8970783&postcount=83028
MATT-H I linked your post into the main vise thread after seeing it . Our resident vise historian found an advertisement for your vise. ( I knew he would ). I am going to guess it is over 100 years old.
https://www.garagejournal.com/forum/showpost.php?p=8969439&postcount=203
This was in the blacksmth vise section. I thought it would get more exposure over here. A quick look around I didn't see any info on this Lewis Tool model No. 64 or 84 ?
The same as my Hollands except the lock handle is a cast one. I bet it is older with with the cool swivel handle. There is no model # on mine ? The collar is staked on the shaft and has some play in it. The jaws are 3" and opens 3 1/4"
You are correct in your guess on removal of the screw. I would put some penetrate on it and soak for a bit. The last thing you want to do is break the head off the screw. Good luck with the restoration and post pictures when done.