Notice the similarity of the empenage rear fuselage to a MiG-21/F/J-7; this appears to be a highly reworked F/J-7, with a new forward fuselage, wing, and powerplant. Incidentally, here is the source of the original picture you posted, Charles:
SoD, yes, it is indeed a very heavily reworked J-7 (MiG 21) as you say. Apart from the rear fuselage and tail in also retains the inner wing on the J-7 - ,onto which new outer panels have been grafted, and the original undercarriage. After all the MiG 21 is tough as old boots and you know what they say about things that aren't broke.