pretty sure it is the right connector for it... looks like this:
and it does fit into the back of the headunit properly.
and yeah the car uses iso connectors for the headunit but i'm not sure what difference that would make to the aerial/radio reception. about the wiring loom i'm not sure about these things but the cars had a new engine put in, so maybe some other things have been replaced (i'm not sure what engine it is).