I did one on my Stratos 326 earlier this year. Mine was cracked on the side that the actuator is on, so I just pulled that half off and replaced it with the same half from the new one. It took me about 20 minutes and 2 beers. If you have to replace the entire valve assembly, it will take longer because you have hoses to remove, as well as a threaded piece of PVC. At least with mine it had a PVC elbow on it, but I didn’t need to deal with it since I only replaced half of it.
I removed the entire bilge access panel because it was the only way to get a big enough opening to get far enough into the bilge to reach everything. It was 8 screws and easy to remove once you tilt the motor down.