Hi Pete, thank you for posting the pictures. How nice to see a virtually rust free shell requiring little in the way of serious work.A great find.
As far as restoration goes, it's good to have a plan and work methodically. I would try to avoid the temptation of unscrewing and removing every single component. and reducing the car to a pile of bits and jam jars full of nuts and bolts. I've found that it's good to put the screws back in the holes. This avoids the possibility of things being lost and forgetting where and how they were fitted when the time comes to put everything back together. So, if you are planning on removing the body, to do the chassis I would leave it fitted as far as possible. You may want to try to get the engine started before you do anything to see how it sounds. It may be fine and not need any work.
You mention wiring and you are quite right. There will never be a better opportunity to rewire the car and fit a few more fuses and relays. The original system of just three fuses isn't satisfactory and does make the car vulnerable to an electrical fire and other problems. Many of us have done this and there's a lot of information if you do a search.
Have a look over on the Club Triumph forum Club Torque. There are a number of GT6 restorations recorded there which I think you might find helpful to refer to.
The above comments are based on my own experiences having done a few restorations and I hope they will be helpful. If not, please disregard them
regards
John