It will indeed have the super K series engine in. I always look at condition of the car before anything else as thats what people see. Then you need to check everything that you would on any car. Then undo the oil filler ontop of the engine and look for any yellow gunk, then undo the coolant tank and look for the same gunk.
As for testing the head gasket you can only do that with a compression test and thats not 100% of a failure. If you fix any cooling problems then it should not goto a head gasket failure.
it looks pretty good on the outside to behonest and it comes with a 3 month Warrenty i think so hopfuly all should be good but im just worried about the headgasget as its done 64k and ive heard its usally arround that mark where it decides its had enough
There is no random mileage at which the head gasket on all Rover 200's suddenly decides "oh no....I must start mixing my oil and coolant now".
Either the gasket is OK, or its not.
If you see signs that the gasket is not ok - i.e gunk etc - DONT BUY IT.
Also, rev the car using the throttle body whilst standing in front of the car at about 4k revs until you see the fan come on - when the fan comes on you know that the car is not going to overheat and thats one less problem to worry about.