bottom end is at most ~60k. But, from what I remember, the guy I got it from(friend of my roomate) said that the whole motor was rebuilt to oem spec. I dont want to say this was done for sure, cause I cant really verify it, but that is what I was told. The guy had this motor in his 2000 civic ex(stock motor, came with his car when he bought it new). He tried boosting it, but couldnt get it to run right, then ditched it for a b20 vtec, and sold us his motor.
head was rebuilt about 10k ago when the port n polish was done.