Kamazuki, all I can say is that you got lucky. I use to work for the largest west coast distributers of used Jap. engines. All I can say is I wouldn't use 99% of them as boat anchors. We would also offer a 6 month or 6,000 mile warentee, that usually wasn't worth the paper it was printed on. Where the co. would make their $$$$$ is on the install. That was $300 a pop and if the engine died the next day, as many of them did, we would replace it FREE, and it would ony cost you anothr $300 for the install.
AS P.T. Barnum once said "there's a sucker born every minute."
Another excellent source of income for the company was little "mom & pop" car lots. They would buy these engines 3 or 4 at a time, clean them up and throw them into some old beater with a decent body that they bought at the "junk" auction. Buying more than one engine would bring the price down to around $150 each. Add that to a decent used car with a blown motor, about $500. And now for a $650 investment plus some wrenching time you have created a $2500 vechile that you will swear was owned by some little old lady from Pasadena and only driven to church.