The Specter replicas all take button cells to power the illuminated reticule, nowhere near enough room inside for a CR123A. Go for a version that comes with a Docter if that's what you want to end up with, that'll save you hassle later on when the ACM tolerances result in screw holes that don't line up.
I've got a VFC PEQ-15 that's not too bad at all, takes 1 x CR123A battery for power. The actual torch and laser are fairly weak, but it's lightweight, and did you want to blind people anyway?