Glad that the tank is going to work out for you. Did you know that the later TR4 tanks did not have the overflow pipe? Just thought that you might want to know as they seemed to feel that it was not needed after all.
Yes, the spire nut that you get from all of the suppliers is all that you will get. The original retainers are no longer available that I have ever found. Actually because I have parted out two cars, I was able to get a set for myself because the car I am driving did not have any left on it. Those spire nuts that one gets are horrible to get off once put on and they scratch up the paint most often. I used silicone calking once to finish putting the letters on and it worked really well.
I don't know about Moss or Rimmer Bros but Roadster Factory does not have the TR4 sun visor. They only furnish the 4A or 250 visor.
Ccharley Fitch
