If the supplemental electric pump is only run when the engine is running, then the factory scheme is actually very good.
Power the supplemental pump direct from the alternator with a relay that turns on with key in run. Use a fuse in the line
or if the draw is low enough, its possible to add a fuse to the fuse box. Its just a pain.
Headlights if used, also benefit from direct from alternator through a relay.
There's a lot of connections for the electricity to get to the headlights - and on a-bodies especially, the wires are small.
Depending on the condition of your firewall connector, for your needs a parallel wire to the ammeter's stud might be enough. Use a well insulated ring terminal.
If the bulkhead connectors are poor, then remove the alternator feed wire from the bulkhead inside and tie in a new 8 or 10 gage wire through a grommet in the firewall.
If the battery feed connection is also poor, then 10 gage with 16 gage fusible link on engine side, then 10 gage through a grommet to the ammeter red terminal.
I thought '63 had the better bulkhead connector, but maybe that was just '65.