Wilhuff could have known Jasper's father. I think they'd have been in the same generation. Jasper is the type to respect his father's friends as he probably invites Wilhuff round for drinks and dinner from time to time. And while he doesn't despise Muggles and Muggleborns, he does think they're inferior so he'd agree with Wilhuff there.
Yeah, Jasper could easily know Antonin's father and Antonin himself from the DEs.
I'd say he'd know the purist side of the Blacks and possibly others. He puts on a front of being a little conservative but amiable so he's not widely known as a rabid purist.