It should fit into a standard Oldham or one of the old Youls, the later is deeper and these are used by Miles to make up his Cree outfits.
Watch out with the battery as they are usually slightly over stated voltage, your emmitter should have a tolerance range, check it out.
Other than that, I am certainly no electronics expert, Mr Mike is your man there.
The battery packs I make up from Maplins parts are very good, but put out about 6.5 volts according to my tester.
My avatar is a poor likeness.