That's a good, effective paintjob!
I take it the older types are the hard plastic and the more modern versions are the soft stuff? If so; where are they from?
I'm still looking for a good source of heads for the modern ones, as I at one point bought a boxload of Iron Man Clix minis, which basically only require a headswap and a silver paintjob.
The heads on yours are looking a bit small for this purpose I think, but still not having found a good source (not even STLs, although I should probably look harder for those), this might be a servicable source.