More questions on restrictor

Ok, so the restrictor has to have a 1/6th hole and the threads have to be 5/16-18. Where do you get these restrictors, are they the standard ones that come as a kit and instead of putting the #1 in at the main it just goes up higher and the rest go into the mains?

Someone said that once the restrictor is put in on #1 up near the cam bearing, that it has to be pluged at the main. What hole is it that gets pluged, the one running up to the cam (small one) or the other 1/2 inch hole?

Do the rest of the mains get restrictors also while doing this?

As for the tap, we used to braze an extention on and it would hold up fine for tapping.