That is exactly the point, "YOU DIDN'T KNOW", but you offered advice anyway. And if others had not stated otherwise the OP would have been misled. People, please if you offer advice, and you are not sure, at least state so. That way it is not taken as gospel.
1970Duster: You could have put it this way.
"Not really sure about a slant six, but roller cams seem to work on other engines. You might want to check on that."