STORING A FRESH BLOCK

Fluid Film, LPS3, cosmoline, axle grease, and a super dry location. Dehumidified, constant temp, etc.

Any of the greases or films should work. Thicker is better. Controlling moisture will be just as important though. Keep it well above the dew point and water won't condense. Constant temps also helps, and low humidity always helps too.

If it's going to be a year or less, fluid Film alone is probably fine. More than a year, I'd be putting on fluid film and then slathering with grease. I'd also warm the block to 70 degrees or so before applying anything - helps ensure no surface moisture getting trapped.

When storing freshly machined parts at work, we just use wd40 but parts tend to get consumed in 6months or less. Parts stored longer get LPS3 and anti corrosion paper, but they're stored in climate controlled warehouses too.