I have an opportunity to buy the engine that I'm going to need for my conversion. Its a stock big 6 and has Motronic FI. I won't need it for a while (~6-8 months) when I realistically think about the other things I can do and the time it will take but even if I pass on it now, I'm going to have to have it setting around, fitting all the other pieces, completing the paint, etc., for 1-2 years (being realistic) before I will have a chance to run it.

Does anyone have any experience on pickeling an engine? How long I can expect it to be okay sitting inside the garage sealed? What's the process?

As this is a substantial investment, it wouldn't make a lot of sense to save $1000 now only to have to spend several times more than that to free it up if it "freezes".

Thanks for any input.

For only 6-8 months I'd give it a fresh oil change and filter, and if you can spin it over a few times to circulate the oil. Drain out any old fuel in the fuel injection system. Wrap it up in plastic, or tape over exposed ports and store it in a dry garage.
Edit: I think you'd be good for a couple years, but you could add a little oil into the spark plug holes too.

or fill it with oil i mean a case of the cheap stuff, pull the plugs and fill the cylinders with oil, drain gas

when ready drain oil and put in proper amount, pull plugs spin it over to clear the cylinders, change plugs and fire it up, it will smoke for a few but it would last 10 years that way

Fill it to the brim with Marvel Mystery oil. Tape all ports and orfices with aluminum duct tape (the stuff used for furnaces and etc)

It can sit for 20 years and be pickled with no issues.

I fill cylinders, intake ports, cases and valve covers to the brim. Remove the rocker arms to keep all valves closed and keep the valve springs from over fatigue.

don't use normal engine oil. If it sits for years it turns into nothing but sludge. Marvel won't ever do that from what I have seen.