I think it'll be about the same as the stock EFI 5.2. He's talking about removing EFI. Power down. Putting on a 4 barrel. Power back up. The 340 manifolds are a step up from non Magnum manifolds, bug if it had Magnum manifolds, and he goes to the 340. Power down.
"Whatever" the stock EFI HP rating is for the 5.2 I think will be real close. I agree with you assessment with the stock 340. But maybe not as much torque, due to the smaller bore. But really who knows? It'll be snappy. Isn't that all that matters?