SOX (and pretty much any Low Pressure Sodium lamps) are rather different from most discharge lamps..! There are dedicated ballasts for them, but I wouldn't recommend running them on a fluorescent ballast. I think you're in the US, am I right..? In which case one of the Fulham Workhorse ballasts might work, I've seen a few people here use them. Bear in mind that with any discharge lamp, the lamp current is key. 26W SOX-E lamps are designed for a current of 0.37A at 59V (on a dedicated SOX-E ballast, which are quite rare) but they will run successfully on normal 35W SOX gear at 0.6A (also 59V).
Don't confuse the designations of the E26 lampholder and the 26W SOX-E lamp though, it really should be quoted as 26W SOX-E rather than S26, but there we go. The lampholder is a standard B22d bayonet cap, most common here in the UK. If you can't find one, let me know, I have a few spares and could send you one for the price of the shipping.
Anyway, welcome to the site and also the wonderful world of LPS lighting, which in my (admittedly biased) opinion, is the best lighting in the world