Slicing it up and VacuSucking will definitely work.
Probably not necessary unless you expect to freeze it for more than 60-90 days or so.
Or, you can portion it up and double bag it (without the pre-cooking) like I describe here:
It freezes really well no matter how you do it.
"Flirtin' with Disaster" BBQ Team (RETIRED)
FBA and KCBS Cook and Judge.
Former owner of a WSM, a Smokey Joe, a Charbroil Commercial gasser (junk), the legendary "StudeDera", a Fast Eddy PG500, and Sherman.
Now cooking with a Yoder YS640
Proud Pellet guy cooking on real wood.