Re: Ignition points.
In the US, 1975 450s were still equipped with D-jet, and the ignition with that system was triggered by points. European cars may have received K-jet before the US. The distributor then, may have either points or a magnetic pickup of eight segments. Remove the distributor cap and have a look.

If you were still seeing battery voltage at all points in the primary circuit while cranking, there was no interruption of the circuit, hence, either no trigger signal, or no amplification of the signal.