Moghrey mie and Bore da, From the West Wales coast. I listen to Manx radio a fair bit as it comes in well hear and has good music. Try carpricetracker.net May help with historical prices. Hwyl.
In many years gone by I did use the 36IV for other uses other than my Land Rover.
I had one on my 1300 Escort.
Experiments with different jets had me a good cheap power up grade [along with other tuning] over the original set up.
Probably cold rolled, likely the most available. Strength wise not much in it for what you need, but cold has a smoother surface finish. 3mm is what I use for chassis.
The only thing I have done to sort a crunched wing id replace the whole thing with a better [not new] one.
However recon you are on more of a restoration than fix up. It is not hard to remove spot welds, there are special drill bits to do just that and they work well. It is a case of rivet to...
Me too, I went through 3 replacements in 3 months last year before I found one that worked and kept working.
A new in the box original Waxstat made one. 👍
Note that is an odd one, if switched on should go at all times the ignition is on regardless as you know.
All I can think is some one has wired it wrong at some time but just a guess.☹️
Usual and best place to connect in your landy is in the right rear under the cover there. And what ever you do do not use those devils inventions "scotch blocks" to link in.