Cool, so the consensus seems to be it's fine. Thanks all : )
The Salsa is 8cm / just past 90 degrees.
It'll be going in a sale thread, I also have a 9cm and a 10cm, PM if you're interested, although tbh they won't be particularly cheap as I paid a little over the odds for them in desperation.
Yes. The connectors are basically the same. Not sure if SP fits on Shimano, but Shimano fits on SP.
Also, how long is that Salsa stem and where is it going to live now?