I hope I dont smell a scam. How was the car idling? Was it shaking a lot. We call that the death shake. I would ask for him to do a comprssion test before you make a commitment on it. You can use a run of the mill piston engine guage just remove the schrader valve. When he cranks the engine you should see 3 solid bumps on the guage. Actually it will look more like a seires of bumps. If there is a major fluctuation at on bump the engine is bad. Or, if the compression is lower than 70-80 PSI its had it too. Be careful. if this engine is in a running car I would ask to see a Mazda Compression test.