I can do my head gasket in under 1 hour, its not a big job. But a recent change on one on a MGF took me nearly 6 hours
Whilst the idea of putting the engine in the back appeals to some, my shovel sized hands couldn't fit down most of the gaps
Look out for water pump problems, and as above bushes on the rear are prone to wear.
Emisions can go haywire if there is a sign of HGF so if its due for MOT it could fail.