I'm currently going through a re-power on my Catalina 38 from a Universal 5424 to a Beta 30.
I opted for the Beta 30 to have a little more headroom for a bigger alternator. Not sure how the engine bed is set up for the A4, the 5424 was using 3 engine mounts. We are doing the modification for the 4-mount Beta 30 which is not a big deal, just some wood laminated on top of the existing stringers.
Happy to snap a couple pictures if you are interested in anything specific. If you are interested in re-building a 5424 I know where to find one as well.