I'm not sure about cost. I'm sure somebody here could answer that question.
I would build the 292 if it were me. It sounds like a good deal for the 292 offered you.
There is a lot of after market parts for the 292 as well. And, you could rebuild the 292 to add a lot of HP + torque. I believe the 350 swap has been over done. I get tired of going to shows and almost all of the classic vehicles have 350's stuffed into them. No imagination any more. But when I see a built six, it's cool. I saw one last year with a blower. I know that's nothing new, but it was the first one I have seen in person.
I belong to the Inliners International organization which is a club dedicated to all inline engines, especially GM engines. They specialize in hot rod six building also. Between them and the people on the stovebolt you can get all the info. you need.
