Well for as long as it's been sitting (in a building but not covered) on its side with no spark plugs in it......
The heads are coming off first just to see if the cylinders are able to be run as-is. There was a rag stuffed in the intake, but it's long since deteriorated to dust so I'm sure there's been a mouse home or two in there. The oil that came out of the pan looked great though......
Dad and I dismantled a 74 F100 this Sunday too. Married C6/205 behind a 3.5" stroke FE of some sort. C4 head on one side, C8 on the other, and a C6 casting on the block. Either it's a 352 or someone wasted their time putting different heads and a 4V intake on a 360; not that there's any difference in 95% of the FE "low-perf" heads' valves or combustion chamber sizes so I'm not too concerned about the heads. Besides emission controls and hardened seats, they're all the same. I'm not pulling the pan to look at piston skirts or heads to measure the bore.