Can some one tell me please,
from the battery, does the power to inside the cabin come through the fuse box only ?
 
where the wiring loom plug comes from the cabin side to the engine bay, does the power only come from the cabin one way?
 
thanks Jim
 

Off the top of my head i think yes. What i have done is upgraded the fusebox to blade fuses and taken the original power feeds to the fusebox to run a relay so the heavier current doesnt run through the whole ignition loom, its a little bit of stuffing around but i think its worth it in the end. You have to remember that all that current is running through up to 55 year old wiring.

Thanks Troppo