I just bought a pair of wheels with one of those freewheels too. I thought I had every freewheel remover under the sun till I came across this design. It is a Maillard freewheel but a Park FR 4 will not fit. The FR4 fits freewheels with 20 splines but looking at your pic yours has 24. This freewheel requires something like the old Bicycle Research CT-3. I finally found one here
http://www.bicycletool.com/normandym...wheeltool.aspx.
Regards,
Jon