User itbparada ported his SVT header down at the bottom most portion of the header. Here are a couple of his pictures for reference. I'm unsure of the possible gains by this, if even at all, but its a picture reference. I don't see it hurting anything however, and its all in your patience and time. I'd imagine removing rough edges in the exhaust this close to the exhaust ports would be beneficial though.
Really, its all in your time and attention to detail. But I think the principles of why an ORP outflows an HFC pertain to this aswell, in which any notable restrictions in exhaust flow hinder performance, although this is on a much smaller scale.