The grip size feels about the same as on my Wilson T3000, which is a size seven! The racket doesn't appear to have a butt cap, so it's the same all the way up, with no flaring at the very end.
I don't have the longer billiards. Never had any problems fitting squash rackets on the machine and I've been able to fit a couple of wooden rackets on there. The Gauthier has the same headsize as the woodens ones I've managed to fit on there, but there seems to be a little less give and stretch in it.
ERSA MRT & Pro Tour Stringer
Head i.prestige. Unstrung specs: 340g, 320kg/cm2, 30.5cm