Suzuki Club UK

your radiator was rust inside, it's make the channel gagged and the water fail running.
when it fail the water steam and less. it will make temperature goes high, but when it happen
it will give you a sign that the radiator water will be less. it mark from radiator cover about 2"
or more. radiator can not suck the spare water in place holder when it happen to replace loss
water in radiator. the radiator must been clean up or wash to running normal again.

you can wash inside radiator with exerting pressure water and brush wire or just with water
and wire (you will surprise when see the radiator feces), then refill the radiator again with
clean water, so can add the coolant, some people believe it can decrease rust in radiator or
can use as watermark (by color) in case the radiator was leak couse rusty from outside.

Looks like you solved the problem with the new head gasket and it sounds like you caught it early.

We'll not know how hot it got to know if it did actually overhaet unless you has steam etc... due to the different sender you've got on your vehicle, but you'll get to know what is hot and what is not from usual use and be able to guage from there.

Take it easy for 500 miles and torque the head down again.

Did you get the head checked for flatness when you took it off. If the head gasket goes again it will be because the head is slightly warped and needs skimming. Hopefully you'll be ok though if you didn't overheat it, it's only really if you overheat it that you know it will need a skim without looking at it.

Hapy SJing then old bean!

kirky