Hello I have a 1989 GT. The car runs very good. When the car gets up to temperature it starts pouring antifreeze from the overflow, from what I was reading online it was saying it’s a bad head gasket. I did a block test and it’s showing that I have a bad head gasket. The oil looks good not milky.I did a compression test and all cylinders were around 148-152 and the plugs look great. Could the car have a bad head gasket and not show signs besides the overflow. Thank you for any help.