I agree, buy a mig welder (not gassless) and spend a few hours practicing on some scrap steel. I'm sure that's the way to go with the amount of welding you mention and you can do it at your leasure!
I wouldn't of thought it would make a noticeable difference that would show on the fuel gauge unless you record the details over very many miles but that's just my opinion, and I'm usually wrong!!!
Using my brand new Nanocom today I found the following fault code:
(10.2) fuel pump drive open load (logged)
Am I right in understanding that when it says logged, this means it was sometime in the past but is not current?
I have cleared the fault code and it now shows 'no faults found'...
Glad you went for the disco in the end, I'm sure you won't be disappointed! With regard to the original radio only having a cassette player, are you sure there isn't a 6 disc CD player under the drivers seat?
Today I waved as I passed 2 disco's, 1 rangerover classic and 3 Defenders and all 6 drivers waved back at me, I was amazed. It may have been because the sun was shining and everyone was happy. First time that has happened when all waved back.;)