Machined parts, Need to store some long term. Humid area. What about gun oil? What are your suggestions?

I can tell you from experence that waterproof grease and WD-40 ARE NOT SUFFICIENT to protect an engine block long term.

I use a product called Picklex-20 on sanded metal panels stored inside recoating every 6 months with excellent results.

http://www.cosmolinedirect.com/?gclid=CJL7oOnF06cCFQnrKgod1g5w-A

It's the same thing that firearms are packed in for long term. It's a little messy to remove, but a parts washer will help getting it off. If they are going to be in the shop the indoor/outdoor would probably be your best bet.

I've had good luck with CRC SP-400 (p/n 03282). Aerosol can, spray it on & it dries to a waxy coating. Couple layers and it almost becomes like rubber. I use it on the boat, protects hose fittings,hyd. valves, etc from salt water, doesn't wash away.

Cosmoline is a great option. The military stores machined stuff using it and it works.

Another vote for CRC SP-400. I use it to protect fracture surfaces to prevent them from rusting. Also used it on my suspension parts after i wire brushed them.

what about axle grease on the surfaces, then a few silica gel packets on top, and wrap the whole thing up tight with the saran wrap stuff they use in shipping large items?

that was kind of my plan for my big block that just came out of the Dakota, to keep it "fresh" while I do the paint and body on my Cuda.

Have you seen this thread?
https://board.moparts.org/ubbthreads/show...e=0#Post6528986

Looks like some neat stuff.