Is there anywhere where I can find the text of the Spanish nusach online? I can find Sefard and Mizrachi siddurim, but from what I am aware, they vary quite strongly from the old Spanish-Portuguese version, as practiced in Amsterdam and New York (and others of which I am unaware).
Koren Publishers have just released a Humash with Shabbat services according to the S&P rite in Amsterdam.
Info on this unique book:
The new Koren Amsterdam Shabbat Humash includes the entire Shabbat service from Friday night to Saturday night according to the traditions of the Spanish and Portuguese community of Amsterdam, Kahal Kadosh Talmud Torah. It features the complete tefilla service for Shabbat, full humash and haftarah readings with instructions in both Dutch and English, making this a wonderful contribution to S&P communities throughout the world.
There is also an S&P Birkon app for Android (free), which has Birkat ha mazon, mein shalosh, and a few other prayers.
If you know the specific text you are looking for sometimes its online (e.g. tzur mishelo, etc.).