if you can set up a default basemesh for the retopo of all, you could also have a look
for a 'base' UV-set: http://www.headus.com.au/doc/uvlayou...-Reshaping.mov
(prolly take the most extreme 2 of all the heads and set up a 50/50
base UV-set to be used for all the heads...trade-off, of course, is that
stretching/compression will also exist for all heads in the textures, but
if it's baking and you don't need to hand-edit that much for diffuse...)
Dunno if Topogun does it, but 3D-Coat
will allow you to bring in a retopo mesh---a mesh that
should be generic to all heads, slightly larger in scale, having the above UVLayout
default UV-set on it upon import---and have it 'snap' to your reference mesh (the higher res sculpted version).
This would allow you to have a very basic default lowpoly template and
spend the minutes adjusting edgeflow according to each unique head.
You can also subdivide and retain the UV's on the above retopo mesh in 3DC, so you could
do minimal (depending on sculpt topology) hands-on adjustment to where you wanted your star-junctions, etc.
Would be a bit of manual labor to get best fit for each particular unique bust, but
seems like a workable option...
(phew...hope all that made sense)