I would slightly disagree with BP regarding the 6v V 12v question, simply on the grounds of durability and maintainability. 12v will always be available as will the spare 12v electrics and even if the CORRECT Lucas (?) stuff ain't around, then the local equivalent 12v stuff will be easy to adapt. I look at it in a similar way to 24v Land Rovers....... how many are still running around on 24v - especially after a 24v alternator failure or short-out! And dual 6v batteried MGB's and GT's. How many of them still use 2 6v's when a good decent output 12v will fit into an easily converted 6v battery space?
Nope, sorry lads. All this concourse crap is all very well if you really want to keep hitting your head but reliability, durability and maintainability win for me every time. Same as nuts and bolts and everyday consumables on restored vehicles. Would anyone really use Whitworths and BSF's when UNF's were suitable and readily available worldwide