bought an intact engine to put in my teener, so...i am afraid to ask...before i put it in my car... Options

[BritCarJim]

what "might as wells" should i do to it before installation. i know that it ran before a tree fell on the car body and the thing sat for 25 years before rescue as a parts car. i will clean up what i can, de-rust, paint, etc., but...seals? things to tighten, loosen, adjust, replace?

[rick 918-S]

Just because it turns does not guarantee the internals are good. If it were me I would at least pull the intake and check the valves from the ports.

Very likely, No actually I would pull the heads and check the cylinders for flash rust on the top of the cylinder. An extra few days to check these things out may be the difference whether you end up with a long term engine or just another short term solution.

So, I would pull the heads, pull the cylinders, Clean the rings, clean and or hone the cylinders, have the valves checked at the local chevy machine shop. Replace the guides if needed and maybe a set of AA cylinders.

The bottom end can be accessed from the cylinder bores. I would take my little hand pump squirt oiler and squirt oil around all the rotating assembly. These parts sat for years and the oil film strength is likely long gone.
New oil will seep into the bearing surfaces and ensure that when you start to crank the engine with the starter your not relying on the pump to supply fresh oil to the bearing before the engine starts. If you have a sound lower end this is the best way to not scorch a 25 year old dry bearing or wipe out the cam in the first 10 seconds of cranking.

Don't put the cart before the horse.