The earlier motors (both 4 and 6) used an Autolite generator, regulator, distributor and starter. The later cars (late '52-'54 both 4 and 6) used a Delco Remy generator, regulator, distributor and starter. You can change a distributor from Autolite to Delco without issue. If you swap an Autolite generator with Delco-Remy you need to also change the regulator and reconfigure the wiring. You cannot do a direct swap of an Autolite starter for a Delco-Remy; not only will it not physically mate up, the wiring is also different. The Autolite starter has a solenoid which requires the starter button to ground it whereas the Delco-Remy supplies 6 volts to the starter when the starter button is pressed. Also, the solenoids are different and require different gauge wires to the button so even if you swap the whole engine, you still need the correct gauge wire or it won't last very long.
The fours and sixes both used the same electrical components (except of course the distributor) so they swap as long as you're swapping Autolite for Autolite and Delco for Delco.
I hope this answers the question.