I have always seen Chinese members here oppose the mere notion that that Israel had anything to do with the J10 program. Where as a little digging will tell you that it was in fact based on the Lavi.
If you look at Jf 17 B, then alot of changes were done to the rear (swept back stabiliser and fully composite tail) and wings (larger).
The idea of a stealthy JF 17 is not too far fetched considering that the US once considered a similar development of the F15...