once it has been taken out of a car. For example an engine that's been sitting in a junk yard, what would you replace? Head gasket set, front and rear seals?

Motor is out of a 90, AAH with 112k when it was pulled, motor ran before it was pulled.

$500 delivered, what do you think of price. Good, bad, can do better.

lot easier than doing it when it leaks after putting it in the car, no?

The one seal or gasket you don't replace is the first one to go after the engine is back in. And it will of course be one that's nearly impossible to replace with the engine in the car.

if it's easy to do now while on an engine stand, I'd say do it. Might cost a lil more initially, but might save you a lot of frustration down the road. w/112k on an engine (judging from mine with 113k+) you're gonna find some leaks... so might as well do it when its easy.

In the end you're right though, it's all a judgement call... but make sure you make the right judgement ;) haha

Check to see if the valves are good heads are good and pistions and such. The seals and gaskets are a must the parts inside the engine should be a judgement call. But dont be cheap or you will be doing it all over again. If its an AHH motor replace the check valves and small things liek taht as well. If you are putting this motor in a car dont you want it to be fresh so you dont have to work on it for awhile. Sensors arnt a must I might Put only hard to get to sensors in andthen once the car starts run the codes for anymore bad sensors.

Clean it up nicly as well.