Finally got the fuel tank back from being modified, I had it made a bit too long so had to have some chopped off and re-welded to fit. I hired some help in exchange for bbq and beer and it all went very well.
A nice bit of adhesive-backed closed cell neoprene went on top of the tank, then the standard Dax straps and foam hold it on. The straps did need some adjustment as there was way too much gap to be taken up by foam and it would have meant the tank could potentially shuffle around a bit so out with the hammer and it was made good. Note the plate at the back of the boot, this bolts through the rear crossmember and then through the straps. We had to take into account the position of the boot lock loop and drilled/tapped holes for it. It fits pretty snug up against the boot lip, from what we could tell from the manual/having a look at the boot lid itself. Time will tell if those holes have to be made into slots!
The position of the original bend in the strap has left a weak point so this will be triangulated with a bit of plate and blobs of weld, then painted up, so I cant fit the tank just yet but its ready for when I make some plates and find a friendly local welder, as I still haven't learned how to weld.
Now the tank fits, and I know the position of the tank outlet relative to other stuff, next job is to put the fuel filter/pump and fuel hose in. I've seen a few cars with very noisy fuel pumps and some that are barely noticeable and after asking questions discovered a lot of people mount their pumps on anti-vibration rubber bobbin type mounts, so I've ordered some and will fit the pump when they arrive.