Hi Cristoph, happy weekend!!!
IMHO the "real" French musketeers - at least for me they are the Dumas-charachterised ones - should have lived in the years of 1610-1630, since Richelieu died in 1643 and Luis XIII died one year later (if I recall the dates correctly...).
However the figures of Glorious Empire (Musketeers Escorte of Luis XIV) are also nice ones - as I can assess it on the pictures - I think the major difference of the musketeers of "our times" is the form of their hat.
So having changed the heads for heads with wide rimmed hat with plum, I think they can be used excellently also in the times 1620-1630.
Maybe I make a try, having just read the fine article of our comrade böckchen:
http://www.intflatfigures.org/index.php?topic=546.0There are a lot of nice candidates for the head among the Droste TYW series.
I have never done such operation so far - if I really accomplish it I shall report myself with the pictures on our Forum.
By the way I am also just waiting for the delivery of the Osprey booklet about the topic.
Best regards-
Sandor