Are you looking for a long-quilled stem or a quilled stem that is long? ie, do you need vertical extension or horizontal extension?

If you're looking for vertical extension, go for a Nitto Technomic or try to find an older SR/Sakae in ye olde parts bin at your LBS. I don't think either come in a 90° version, though. Hopefully the 71-73° range (parallel to the top tube) would be ok. For horizontal extension, your options are plentiful - Salsa is a good choice. You won't need as much vertical extension if you get a stem with positive rise, so the shorter quill length on the 90° Salsa might actually work out fine. I'm pretty sure Salsa also have a 105° version of the SUL, so that's also an option.