The DASH2 / Syvecs combination is well proven and works just fine
Speed and RPM can be input from the ECU no problem, but you will need a custom firmware for the CAN <> DASH2 converter from Race Technologies, since they output ECU Speed on the "wrong" channel for the dash to display by default. They are very helpful and will email you this firmware if you ask them, you just need to explain that you want speed from the ECU
In terms of the CAN datastream from the ECU, it is called "Custom CAN", mostly because it is customisable.... you can tell it what you want sending. The default Custom CAN setup is normally adequate, but if you want certain non-default parameters then you just alter the setup of the stream (it is really easy, you just choose off a menu what parameter you want sending in which slot of which frame).
Not all the Syvecs parameters are directly supported by the DASH2 because it isn't aware of some of the concepts, BUT, you can send auxiliary prameters to the dash and you can configure labels on the dash, so you could send Calibration Switch position as AUX1 but then instead of the dash displaying it as AUX1 you could get it to display CAL instead. So you can "make it work" by being a little creative with the way that you send parameters
We can supply a working configuration to get you started and so you can see how it all ties together if you would like
Hope this helps,