On the 650 I assume?
When you say upgrade the charging system, you'll be looking at a 3 phase alternator stator, & a solid state regulator/rectifier like the PodTronic or Boyer units. As I understand it the original lucas ones were 180 watts (RM21) but I think there might be modern equivalents with an output of 210 watts, unfortunately I can't recall from where.
I'm not really sure what sort of current draw the ignition systems have, but any of the 3-phase units will have sufficient capacity for decent lighting & igniion. I don't know of any source for alternators of greater output than those I've mentioned , although I'm sure they could be custom made if funds were unlimited!.