the guy in the cowboy hat looks like Speedy Bill from Speedway Motors, he has the largest collection of these kinds of esoteric concept motors in the world. i wouldn't be surprised if he owns one of the 2 cassiopia motors as well as that 289 SOHC motor. i think that 289 SOHC motor may have also been a development mule/prototype/predecessor of the gurney eagle/weslake motor as well.
you have to keep in mind this thing was developed in the 60's, 30hp over a stock hi-po 289 was quite a bit, Shelby even inflated the numbers for his mods to the hi-po for the gt350-s to 306hp, i seriously doubt that an intake, carb and tri-y headers added exactly 35hp to the hi-po's base numbers