The Perkins 4-108/7 is 36hp at 3000rpm. Never seen one run at any other rpm on a boat. I think they were in taxi cabs in England making 50hp at 4000rpm.
Nice to see that some manufactures offered a range of engine options. If I had one I'd probably opt for the twin 108s. Rather have a newer engine though. I have a 4-107 Mitsu in my 30' Willard. It's a very good but not particularly modern.
North Western Washington State USA