OP, if I were you I’d get it fixed by a reputable dealership and then sell it right away. I wouldn’t want the potential of failure clouding my mind on the track.
I have 134,000 on my 2013 brz with a build date of 07/13 and I’m keeping this car because I trust this engine more than any other engine Subaru has made. I was not flagged for the J2 recall, but if I had some 20 year old take off the heads and experiment for a fun story to tell his buddies, all that confidence in the engine would be lost so I do understand where you're coming from.
It sucks your track car “soured” but at least you won’t have to worry about this with your future 2015+
