how do i test to see if a engine is good if its not in the car anymore?

back story
i just found this 88 SE N/A that a local guy is selling for $100. he told me that he got the car from a old man that had Mazda put in a new 0 miles engine in and drove it for 10K before it had starting issues. the old man let it sit for a year before this guy purchased it.

Im thinking a electrical issue like timming or maybe even fuel. but can a engine with 10k on it be bad?

my story: i need a engine by monday that works, i am swapping it for my engine that has blown water seals in it.

Opinion part.

SHOULD I BUY THIS?

 

Yes, assuming the guy has the receipt.

The WORST that can happen is you're out $100. The best is that you get a 10k mile engine for $100.

And it's possible, but HIGHLY unlikely for an engine to get fucked up in 10k

 

Jump on that car. If you have room to park it, if it is indeed blown, then you could easily make that money back by selling parts.

 

The Engines out? Take off exaust manifold and try to see in it and see if theres rust? Id Get it.