Contacted this company a 2 years ago to buy the FIA heads for Ford 289Informed that they had to fulfil the 1965 Shelby GT350 FIA spec – “no problems” they saidGot the heads – nice ported. One head had a 1966 casting and the other one had 1967 casting – not OK but I decided to use them anyway.After about 10 hours of usage number 4 cylinders exhaust valve seat fell out and of course damage the rest of the engine.Took the head to my machine shop – he did not want to even try to repair the head. At a closer look, there was an additional thin metal ring outside the valve seat ring (as is the made a too big hole from start and tried to patch it up) and there a few traces of Loctite as well. My machine guy sad “there I probably more of this careless work on other valve seats.So the heads were junk.No matter how nice the porting is – if the valve seats fell out you can´t use.Posted a note about this on Power Heads contact page– but no reply.Bertil Carlson / Sweden