I run a 55A Alt with Fogs, power Windows, Radio, Seat Heaters, H-4s, heat blower fan, two spd wiper, oil cooler fan, alarm, and map lights, plus the regular lights, engine, etc.. IM does it with relays and their own harness.
If you look at Street Rod or Restoration wiring harness set ups such as "Painless" you will find they start with a basic set up and then add options you may want, such as radio, power windows, yada. I used one of their harnesses on a 54 3100 1/2, with several options using an old alternator (converted from 6 to 12V) and have had no problems running amps, radio, power windows, power cowel vent, interior lighting, heater, ac, etc. It's just a matter of having the right size wires, good fuse block(s), relays, etc. Street Rods and older Retro set ups are not that much different than a Speedster R.
IF you are re-doing wiring on a VS. I highly recommend you pull out that less than ideal fuse block they used in 2001 (maybe it's been upgraded since then?). A few owners can testify to that VS issue. (I think Paul Harford mentioned it recently) I replaced mine with a good aftermarket Fuse Block after the VS system "fused together" and set off the car alarm 10 miles from home. I would go to one of the wiring harness manufacturers (there are many, but I had good luck with 'Painless'. Tell them where your battery is, the starter, grounds, what you will be running on the system, maybe draw a rough schematic with dimensions, etc, and let them send you a system that you can install yourself complete with the right guage of wiring for each application, relays, good fuse blocks, in line fuses, tags for all the lines, color coded, connections, etc.
Is this an Overrider thread?