I finished up using the 240 and a 50mm lens at a distance of around 70 metres. Then split the tower into four segments using a 200mm prime for detail pics that should give him all the info he needs. And as someone pointed out he will probably be working from a set of plans from the people who build the towers ... this just gives an idea of actual construction and finish.
It was smoking hot out there in the sun at midday today and the flies were horrific.
Not exactly a glamour shoot but it was quite challenging and I really enjoyed it. Thanks for all the sound advice.