I'm sure it could have been welded but put yourself in my shoes. The two welders I spoke to said that a bolt was the way to go. I didn't want to trust some inexperienced yahoo who fucks up my manifold when a simple plug would do the trick. The only thing that's sure is it's tricky and nobody could recommend any welders that wanted to even try...including yourself, Juicy.
So they were out of steel 1/8" plugs at True Value ( I told the fuckin guy to hold me one but he refused) so I got a brass one and a couple steel 1/4" plugs.
My hokey patch job was holding just fine. I pulled out the probe and cleaned up the threads of the hole with the 1/8" tap and tried the brass plug. It seemed to grab with only a few mm of threads left but I figured that was enough. I think it was probably sticking into the pipe by a 1/2" at the most but I took the angle grinder to it and shortened it anyway. Then I cleaned the threads up on it with the correct die from my coworker's set and screwed it in. I feel like I was only able to put like 4 or 5 ft/lb on it at the most but it only gave off a small bubble before sealing up...hopefully for good. If not, I've got the larger plugs I can use one of.