I bought a "newer" 99 a few year back because I always like them and never owned a lever gun except a Red Rider
It a 70's vintage 99E in .308 caliber. I think I paid $350 for the gun, a couple boxes of ammo, a set of dies, sling and a soft case. My neighbor grew up in VT but gave up deer hunting and his son wasn't into guns or hunting so he decided to sell it. He asked me what it was worth so I did some research and told him it was probably around $400 since he had stripped the original finish and oiled the stock with "Swedish Oil". He said "give me $350 and you can have it". So I did. I don't think the 99E's are worth much. It's basically the mass marketed Woolworth version of the gun. No pretty wood or anything special. Just a shooter. It came with a Weaver K4 scope on it. I also have a Remington Model 600 Mohawk in .308. Another odd duck, Woolworth gun. I need to take them both out to the range and run some rounds through them. Sounds like you gramps's 99 is a keeper.