Do these lamps use a 700-series phosphor?
https://www.amazon.com/Philips-281618-Fluorescent-Lumens-Phosphors/dp/B008VJCVFO
Recent datasheets claim the use of a 800-series phosphor but older datasheets do show the use of a 700-series phosphor. Being USA made, they might be old enough to still have the 700-series phosphor, although I am unsure.

@Multisubject, After reading some Advance Catalogs, I have seen that they did list some 480V 60hz only series reactor ballasts for 35W, 55W, and 90W SOX low pressure sodium lamps.

For the 35W and 55W lamps, the 480V 60Hz reactor ballast designed for them is part number 71A0440. For the 480V 60Hz reactor ballast for 90W SOX low pressure sodium lamps, the ballast part number is 71A0540.

From those particular ballasts, I am sure that the 480V line voltage alone was just enough to ignite the lamps.

That was my idea, too. Wander what lifetime penalty is on each start...

True.

At the end of the day, it’s your light. If you were able to find someone who is willing to repaint it for you, that’s excellent.

Well, the people who are going to refinish and paint this said that they were intrigued by it so I figured I'd hand it off to them and they can fix it better than I can especially considering that I don't have the right equipment to do so.

My 100w SDW-T ballast makes some nice growly noises during startup. First time i turned it on, i thought something was going very wrong. But that goes away after only seconds.

Nice! More 400W fixtures! I have two thorn MBI-400's I need to finish up one day. They both have dead igniters. I have replacements. Just haven't had the time to fix them yet. I have a new old stock reflector so I'll be able to make one of them pristine, the other will... Look a bit meh. But they will both work! Massive power users, but they're extremely cool and no amount of other lamp technology comes close to how impressive I think these big things are! I have a few spare lamps but not a huge amount. They last a decent number of hours, but they're driven really hard!

I've seen Philips SDW-TG 100W rectifies for long on an electronic ballast: https://www.lighting-gallery.net/gallery/displayimage.php?pos=-251959

@James  noted that SDW(-T) electrodes are just straight rhodium-tungesten rods, without familiar starting aid coils. That means these lamps are expected to be quite hesitant with glow-to-arc, until electrodes and arctube become hot enough.

SDW(-T) lamps actually glow-to-arc somewhat faster when on squarewave electronic gear.