I'm assuming you still have time to prepare...
If you're gonna buy an amp head...yung minimum 4 ohms ang impedance para pwede sa 4,8 at 16 ohm speaker/s.
Try mo gumawa (or magpagawa or kung may nabibili) ng speaker cable na Male connector yung isang dulo tapos yung kabilang dulo ay "speaker forks" or "Y". Hindi ko alam tawag...basta yung kinakabit sa speakers..
Then lets hope na:
a. Open back yung amp. Pag closed back, im not sure kung papayagan ka tanggalin yung cover
b. Match yung impedance ng speaker sa amp head mo
b. Hindi fixed yung connection ng amp sa speaker.
b. Payagan ka i-disconnect yung speaker
Good luck
PS: Do you have an "exception" na kung yung amp na yun ang nasa venue, hindi mo gagamitin yung amp head mo? ('59 Bassman, '63 AC30, Dumble, Mesa Boogie King Snake maybe?) haha