If you want to put something under the brick then some wool will do, or you could trowel in a blob of that Rutland. If you have some more alumina it could be used to connect the wool to the brick although that isn't necessary.
That's a creative idea about the hammer heads but I don't think I'd try that with conventional welding. You really need one piece of steel and you won't get there with an arc welder or acetylene or TIG or whatever but you could get there with forge welding. Problem is, you would need an anvil to accomplish that task.
So, in your case you need to start with one piece I think.
Know any place that has old wheels off a railroad car? Worn out axle off a bulldozer? Any kind of solid steel rod about 3 or 4" in diameter would be a good start....