There is really no reason to do an 'integral'. Most integrals are designed so that any ammo will be subsonic, but it most pistol caliber 9mms, 147 grain and heavier will be subsonic without additional porting. Subsonic 115 grain is pretty pathetic, and one of the reasons you don't see SWAT teams using MP5SDs any more.
I would do a muzzle can, and move it around between different 9mm guns, if I were you (unless you're having a historic clone made). Having said that, I think Doug Melton in Arizona (SRT Arms) will make anything you want to pay for. I'm sure there are others.