All Plugs Fouling on Right Bank

Yeah that's your problem!
But not only that, the blades were milled to get the slot exposure back!, You're in big trouble!Actually the milling appears to be factory. But I have never seen milling like that before.But then I have never been under the hood of a 65 Commando. No matter, the holes need to be closed up. They are waaay too big for any cam you might ever put in a 273.
The usual way is with solder, I have soldered up quite a few. I take a drill bit about twice as big as the holes or a little less and, by hand, chamfer the holes, both sides;about 1/3 of the way through.Do not use a single speed electric drill;if the bit bites, you can kiss the blade good-bye. Then I heat up the plate and melt a little drop of solder into the hole. Easy on the heat;you can ruin a plate pretty easy with a propane torch. I use one of those mini, butane pencil torches. After the solder cools I dress it down almost flush.I usually remove the blades for this operation, but I can't recommend you do that, and if you try it, you will find out why. The screws are staked. If you try to remove the screws without grinding off the stump,you may destroy the screwdriver slots. If you manage to get them out this way, then putting them back in will be a treat. No, the stumps have to be ground off. But then how will you prevent them from unscrewing themselves and falling into the engine. Well, I use loc-tite there no problem. But another trick is getting those blades back in so that the throttle blades actually close up tight. And there are two of them. So, all in all, I recommend that you not remove them.I know what your thinking; you can't solder those holes up while the blades are installed.Ok then figure something else out, but get rid of the holes.Sorry, my bad. You can try a plastic rivet. But if you are thinking of JB weld, you didn't hear that from me.That stuff turns into stone when it hardens. But if falls into your engine it will turn into a grinding stone. I suppose two-part epoxy would be ok. But it's kindof tricky in that it want's to sag and fall out of there before it sets up. I seen one guy put tape on the bottom-side and then dripped some into the hole.
But if you separate the throttle body from the rest of the carb, you should be able to solder it up.
The beauty of solder is that if it ever falls out, at least in my mind, it can't do any damage. The plugs in my 750 have been in there since 2002, and close to or over 100,000 miles.
Once they're closed up you can screw the curb idle screw in, just enough to make those transfer slots a bit taller than they are wide,set the mixture screws to about 2.25 turns out from lightly seated, and let the T-port sync begin.
BTW; what are those pointy spikes just off to the left of the holes; I haven't seen those before either.