The dyno numbers in the end show the 312B2 reaching 365 horsepower, and BangShift notes that it's most likely an endurance engine build, engineered to withstand use for a lot longer than the 1970s F1 races lasted. As the engine builder, Carobu Engineering says, it is "a standard rebuild on an existing engine platform with no additional modiﬁcations for power. The primary consideration was reliability and clean running. While not the most powerful vintage F1 engine, it has been very reliable and smooth."
Carobu's video commentary also says that the engine was originally received with broken timing gears when they first rebuilt it years ago. The first build produced 289 horsepower at 9000 rpm, and the second rebuild made 365 horsepower at 9800 rpm thanks to improved injection system tuning and ignition optimization.