For years I've heard that Chrysler Marine never built a 426 Hemi. I just bought book of every Chrysler Marine Service Bulletin from 1964 to 1971 and dated 11-20-65 is a eighteen page spec sheet on the marine 426 hemi.
525 HP @ 6400 RPMs
490 Ft/lbs 4000 RPMs
left hand rotation only
12.5:1 Compression ratio
Twin Holley 4bbl carbs on cross ram intake
copper monel tubular/jacketed exhaust headers
72 C velvet drive