I have no clue. It'd probably just end up as a wall hanger. I've got a bayonet a friend of my dads brought back from the war so I just need something to stick that on.
For a while in Florida I'd see them all over gun stores, priced below $100. I never got one, mostly because I wouldn't know where to get ammo from to feed one.
I haven't seen on in a while. I'd hold on to it, and ask your grandpa where it came from. There might be an interesting story attached to that gun!
A bolt will set you back about $50 but the work to reverse the weld will cost quite a bit more. Strip it for parts. I tried to sell an all-matching Type 99 for $150 and nobody would buy it. I stripped it and sold all the parts separately on eBay and made $350. And the stock more than likely isn't cracked. The Japanese stocks were purposefully made in two pieces as it then took smaller pieces of wood to complete a stock. Since there is no real connection to your grandfather I say hang it on the wall or part it out.