There is no "right" way to do an 8-volt battery installation, and I grew up around a shop where we had the best charging system tech in the southeast- - -my father!.
In order to recharge an 8-volt battery, the voltage regulator must be set at 9 volts. That burns out bulbs, headlights and everything else. It's also rough on the gas gauge and all the other electrical accessories including the coil and points. Normal charge voltage is about 7.5 volts with a properly-adjusted regulator working against a fully-charged 6 volt battery.
Big battery cables, #0 or larger, and very clean connections and grounds will keep a 6-volt system starting just fine except in extremely cold weather. Make sure there's at least 4.5 to 5 volts available at the "+" side of the coil while the engine is being cranked. Dirty contacts in the ignition switch or poor connections between the switch and the coil will rob voltage from the coil, resulting in a weak spark, even with good cranking speed from the starter!
Jerry
