Defender 200tdi refresh

Hi, I have a 200tdi converted defender which I've owned for 15 years. I've put a new chassis on it about 6 years ago and am now thinking about the engine. I would like to use it to tow my enclosed car trailer and so want to try to optimize the power of the engine. What is the best way to do this? Rework the head? or a complete refresh of the whole engine?

Thanks

Probably need to check the engine condition first, how many mile has it done , test engine compression,
Quick win is set the valve gaps how does 0-60 compare with spec, what’s it
Iike pulling up a hill
Are you handy with a spanner , I refurbed my 200tdi engine and was surprised to see minimal wear in cylinders , stil showing honing marks , I changed bearings and a few other bits and hood to go
My thread is on here