Probably your best bet is going to be to set up a watch on eBay for Blue Point Bench Grinder. Right now, there isn't anything there that matches that particular model, although there's another similar Blue Point one, also missing some parts, but it's a different model, and doesn't match yours.
Eventually, one will show up there, but it could take a long time before you find the missing guard and other parts you're missing. However, the one on eBay right now is asking $109 for the incomplete unit, so there's some value there if you could find the missing parts.
Problem is that it's old enough that parts aren't going to be readily available, I'd think, and you'll have to wait until something shows up, probably a complete one, on eBay. That's probably your best bet, really.
I don't think Snap-On will have parts for one that old, but you could try.