Overheating in Freelancer petrol 1.8

I am Kajiadohugh and this is my first post. In 2008 we sent an 02 Reg 1-8 Petrol Freelander out to Kenya. Initially it was fine but then started overheating , particularly in slow moving traffic or in
temperatures in excess of 30 degrees C . It was in hindsight the wrong vehicle and has had major head gasket problems . Rather than repairing again we are wondering if we can put in a Japanese engine or a freelander diesel engine from a crashed write off.
I would welcome your thoughts and any relevant experiences
( 4WD is important to us)

Anything is possible, but replacing the standard engine with a properly maintained or repaired 1.8 is the easiest thing to do.