Yep how it was stored is definitely going to be an issue. I had mine rebuilt years ago and then lost funding for the project. I took out the push rods and that sealed the cylinders and relaxed all the springs. The rest was buttoned up with cheap gaskets. I just opened it up for a look last summer and it is still all nice and shiny metal but I will still go through the whole thing top to bottom before I fire it up.
My motor cost just over 2 grand in 2008 for a long block, just to compare price.
Who rebuilt it and what is the price?