I own a 78 Cat 27 IB and changed out my cutlass bearing and I agree that you should check with the Cat 30 owners website for the design of a tool to do it. I made a split puller/pusher to remove and install the cutlass bearing without having the remove the prop shaft or rudder, just the prop. It took a bit of work to fine tune the tool but it worked a charm and the whole job took about 2 hours with the final version of the tool. I was surprised to see virtually the same tool design on the Cat 30 web site later on. It sure is nice to not have to drop the shaft, or rudder and just remove the prop, push the old bearing out and then reinstall the new one.
Note: It goes without saying that it is very important to lubricate the cutlass bearing before starting and running the engine with the boat out of the water if there is any chance of the shaft moving (which there is). Ken