Interesting. I don't have any specs in front of me, but I was thinking the engine of those years were weaker then the 88 & up.I was shopping for Mustangs a while back (never got what I was looking for, though I do have a Fox-body car now, just not a 'stang, lol), and was always told to go with the 86-87 GT 5.0
I was told those were the last years of factory forged pistons, so could do more on the top end without having to rebuild the bottom end of the motor right away.