do you need to store extra cylinder heads long term without rust/damage?
buy a few military surplus

Medical transport boxes
Size: 31" X 12" X 19" weight 26 lbs $30

they are air tight, fit heads, stack and store well long term, Ive used them for years to store heads, just spray the intire heads surface with LPS #3 wrap them in a dozen layers of news paper, insert them in a plastic garbage bag, then place them in the box and seal it, place the box on a shelf and your great grandchildren can open the air tight box and find heads in good condition 50 years from now

http://www.calarmy.com/containers/boxes/otherboxes/