look at the trunk...right where the rear window and the trunk meet thats where most of the rust was on my dads 66 mustang...so im assuming because of the window and the angle it might be the same just a thought
it should be visible on the little chrome strips around the back of the window and where the roof meets the trunk
u might also want to think of "how bad" the rust is a little rust in some spots isnt to bad some rust is ever almost normal on a car that age rust is in no way bad but sometimes the good deal on the price can make up for a little grinder work and some paint just a though =)