Welcome to the site. I hope it's nothing major. As long as you didn't let it get too hot for too long, you probably didn't do any damage.
I see you found the SVT tech page. That's the best place for your question. Enjoy the site, and I hope you get a cheap and easy solution in fixing the car.
Check the oil and coolant for any mixing, due to a head gasket. If the had gaskets are OK, I don't think that the problem is gonna be too major.
'88 GT convertible, 5 speed, 3:08 gears, A9L Mass Air conversion. Mac shorty headers and H-pipe, Magnaflow catback.