Having worked in the automotive industry (and even in this specific maket) for a number of years I would NEVER just drop ANY used engine in a car.... even if I hated the person. You have absolutely NO idea what it's been through and trust me, low mileage means NOTHING with a 20+ year old engine which has possibly been beaten to hell in what road life it has seen. I've dealt with plenty of "bulletproof" engines which have died terribly with less than 20K on them (even after testing out just fine prior to installation).
Mostly bicycles? You think it's China huh? They've got more technology open to them than that.
It kills me how people think it's that hard for kids to find open road upon which to beat the shit out of their cars on anywhere in the world. Even if it's not driven daily it doesn't mean it's not run low on oil or over heated every weekend; It only takes one screw up to start the time bomb ticking.
A JZ install isn't a straight drop in and many people dig themselves into a hole because they can't do what's needed or afford a competent mechanic. It's a bad idea to just throw it out everytime without explaining the pitfalls. I've seen a lot of these projects sold for pennies because they couldn't afford to continue or just gave up.
And 100 posts doesn't mean much, when I came here I had over 2000 posts on most of the other forums I participate in... Low post count != newbie.