That's a nice looking rifle, someone did a nice job on the stock carvings, however that's not my cup of tea.
I have two 99s a 300 and 250 Savage, they are sweet rifles.
The biggest thing I've shot with a 300 Savage was whitetail deer and I sure dropped a lot of them with that caliber.
A lot of the deer I dropped were running shots and I attribute the natural swing of the 99 to helping me make those shots.
As for what your rifle is worth I can't really guess, I do know a collector would want the rifle in original condition.
Shoot the rifle, try a tang peep sight I'll bet you will enjoy it.