The 1.2 HP per CID assumes a V8 with greater than 9:1 compression and proper selection of fuel, carburation, valvetrain, heads, ign, and exhaust systems. I've got a Pontiac 400 squirreled away for a 1.2 HP per CID project. Bored .030" will give 406 CID. You do the math.
*evil laughter*

chip

Preaching the Hot Rod Gospel according to the 4-stroke apostles:

Suck, Squish, Fire and Fumes