Come on guys, let's not nit pic this, leave a little meat on the bones. Assume he raised the compression ratio a little at the time of boring (I would, I know you would), maybe a little head work, along with a cam, intake, headers, exc..

A standard 350 block does not have to be 4 bolt mains to make decent power, 365hp 327's were all 2 bolts and there are tons of them out there bring down 300+HP. Give the man a little bragging rights, 300-400Hp is a reasonable estimate for the motor. Could it be less yes, could it be more, probably not. But we don't have to insult with 100HP estimates (geeeese).