1st: The wastegate is internal, and integrated into the turbine housing itself. You won't be swapping the wastegate, but just the actuator itself.
2nd: Yes, you can make it work. It may require you to fabricate some sort of mount to hold it, but it can work. Don't be afraid to build something out of hard metal strap pieces.
I'd reccomend an actuator from a bigger turbo before one from a smaller turbo, though. The actuator from the CA is going to run less boost than the SR actuator would, and its pretty weak and probably worn out from years of abuse anyway.
A good aftermarket actuator or one from another OEM turbo vehicle could be fabricated onto your SR turbo just as easily as making the CA actuator fit. In the end, you will have steadier boost, a wider power band, and the ability to hold higher boost most likely.
This actuator was an adjustable aftermarket piece. We built the bracket from strapping material we got at the hardware store. It's welded together and then JB welded and bolted to the actuator itself.