For the benefit of anyone intending to make conversions using the Red Star range and Perry miniatures here is a quick thing I threw together. It is a Red Star head with Bigeard Cap on a body from the Perry plastic Desert Rats box.
I leave it up to the reader to decide what works size-wise and what can be done by a bit more work on the neck joint, but this will at least show you the size Red Star with Perry.
I have done another head swap on a figure from the Perry plastics box. This is a Warlord Celt head used to make an LRDG trooper.