Any gustimate on the parasitic loss from the chain and associated dyno stuff? You may be closer to 300 than you think!

OT: When you say 'Beast', I think of The Beast of Turin.
Four cylinders, 28.5 liters, 1900 RPM, and about the same HP as you're getting.
https://www.youtube.com/watch?v=0TV2l6TOuGA