No, The heads must come off to do the repair, and pull the valves out to reach the hole, might be easier from the valve side. The head studs will not let the heads off with out pulling the motor, so...
The TIG electrode did not work, well, it worked a little. The joint is much too brittle like cast iron repair, and the tungsten has a much higher melting point than anything else which is why we use it. Cranked the laser up to 400 volts and blew the rod in half so I had enough power to do the job but I see the right way it is going to be a heated jig that holds the angle and run it up to 3000 degrees then start the laser and at the same time rotate the jig all inside an Argon bath. Damn, and I left my resistance welding machine to do the preheat in China 10 years ago. Probably have to make the jig out of Carbon..
It did work and I will post pics tonight but it was too delicate and would not stand up to normal welding rigors so I played with it for a half hour and stopped.