Cylinder head rust removal

I got my two sets of heads back from the machine shop and i have one good set between the two. they pulled the valves and springs and fluxed them but they have some rust in them and i want to get it off/out. anyone know the best way. or is the acid that everyone is using for other rust removal the way to go

 

Vinegar only removes the rust & it's cheap.

 

ive seen people use vinegar for rust just wanted the word before i soaked the heads in it
Thanks.