The best thing to do is plug it at the head and water pump so the coolant will pass all the way through the head where it belongs. Unfortunately those block off plugs are meant for temporary use. I had mine blocked off with those plugs at one time and when I removed them they looked like they were going to fail at any time. For that reason running a bypass hose may be the best route unless you can come up with a more permanent plug method. A half assed but effective way would be to use short pieces of hose and insert some sort of plug and hose clamp it up.