IO540
UK or USA you have to be careful who you use, I have done a lot of flying in the USA and seen that there is a big difference between the best and the worst.
I am sure that Silvaire1 & SNS3Guppy could tell a few tails about who not to go to in the USA just as they could recomend some reliable workshops who will do a good job at a fair price.
I know that you have the ear of a few people in the UK maintenance business, they can tell you who will do the job to a high standard and have the paperwork to back it and more impotant those who don't and can't.