A buddy who had another SD1 V8 once opened the bonnet at night with the engine running. You should have seen the 'fireworks' display of lots of 25kV leaking and sparking to earth all over the engine! Dunno what make of high tension leads he was using, but obviously not very good ones.......
been there! customer came in on a dark autumn night...car wouldn't start and he'd bumped it down into an unlit lane without success.
Opened the bonnet ,owner cranked and I watched the scale model Aurora borealis under the bonnet... "hold it" ,sprayed a liberal wafting of WD40 over the leads and ignition, with a gentle breeze behind me..."Right, try it" click WHOOMPF...A mighty sheet of blue flame leapt up the windscreen....and it started.
I learned something that night
[quoteI was saying distrubute the 12V to each cylinder, NOT the 25kV, and step it up at each spark plug.][/quote]
given the materials of the day, I think you'd have struggled! multiple points would have been possible, but the coils would have still been large ,given the insulation and manufacturing techniques available, not to mention all the dodgy LT connections needed.
PVC insulated copper leads were the least trouble but they were outlawed when the resistive carbon-impregnated supressor-leads were developed. (they, together with resistor-plugs go "high" and cause all sorts of problems, but some electronic systems NEED the resistance in order to work!-shorting -out a lead can kill the ignition module
The present system is, by and large, less reliable than the single-coil/dizzy model, though i just recently dragged in a Golf with the square-frame coil cooked. (bulkhead mounted)....the ones on top of the plugs get cooked, leading to premature failure...then you HAVE to buy the dedicated stick of all 4.