UPDATED. Newbie dual bowl master cyl 66 stang conversion question (drum/drum non-power)

Although user POS sounds like a knowledgeable dude, I meant to ask the group this (since I'm brand new here I thought when I started a "conversation" I was speaking to everyone...anyway...trying to fix this problem this afternoon if someone has an answer and can reply (BIG THANKS).

I bought CJ Pony's dual master cyl conversion kit for 66 drum/drum non-power brakes car. Bench bled it, installed it, everything's ready except the 2 lines between the Master Cyl and the brass block.

Update: Question 1 below is Yes!. A 3/16" to 1/4" compression fitting (from Advanced Auto Parts) solved the problem.
1) for the line closest to the firewall, the male end going to the brass block is smaller than what I have, so it doesn't connect to the larger hole. Is this simply about getting an adapter from a good hardware store?

Update: for Question 2 below, ok, i'm a dumba55. CJ's video DOES SHOW -- IN THE VERY BEGINNING (the part I skipped past) show where you put the brass plug - where the rear brake line used to go.

2) Most important question: Kit comes w/ the two lines, but also a brass PLUG that has something to do with converting from single to dual. I watched CJ's installation video twice. As we say in Baltimoreze, "I ain't no mechanic, I ain't!" WHERE DOES THE LITTLE BRASS PLUG GO? I'd love to get a reply today if you have a minute so I can get it done.

We're all set! thinking the front port on the Master Cyl gets blocked off by screwing in the tube and adding the brass plug to the end. I'd love confirmation of this though before I go further, i.e., bleed the brakes yet again, and drive it as it will be her maiden voyage.

Thanks, Bob outside Baltimore, MD