If you keep 6v fuel gauge / sender etc, it works, but shows about 1/8 of a tank full when its dry and empty. I know as my petrol pipe split and emptied 20L over the driveway, which seeped through the house walls, under the floor boards etc and the wife wasn't too impressed !!

Shouldn't imagine she would be! 6v gauge & sender still in use, also clacky indicator switch, seem fine.
Interestingly, I'm using the current (black, square) indicator relay ECAS sell, with a 12v 21w bulb in the original, body side, indicator & the LED bulbs I was using with the 6v in front and rear inicator lights. It works fine, I thought I would need 2 x 21w to make it run @ correct speed, but no. However, if one of the LEDs is out it runs 19 to doz. & without the 12v 21w bulb it won't run @ all....

Send me your 6 volt fuel gauge if not needed,cause i'm going back to 6 volts

Er... fuel gauge is still in the car, running on 12v, seems perfectly happy. So sorry, no, I still need it!

I tried the 12v 45w halogen bulb in line with the 6v wiper motor, which seemed to work fine, but on the Imber Raid the wipers got slower & slower & finally stopped. Don't know yet if this was because the set up didn't work & 12v killed the 6v motor or whether the (presumably) 50 year old motor just died. 1980s 12v wiper frame & motor now fitted, runs a fair bit faster than the 6v + bulb did on 12v - which makes me think the 6v motor was not killed by excess volts. Running it (6v) briefly on 12v produced a manic speed.

When I sell Gerty I will put her back to 6v.