Seriously use the 2/3 gallon bakery buckets from the grocery store. Most places will give them to you. I have found the seals to be not quite 100% air tight on some, so for the heads I want to store for a really long time, I also bag 'em up and O2 absorb each bag. For a head I plan on using within a couple years I just O2 'em.
Do you have enough hoarded or are you still prepping these heads?