Re: carb cleaning help - 1985 70hp johnson
Looks like a rebuild to me.
"Core plugs" -- that guy just pulls one off the shelf (professional mechanics got parts inventories), but they're included in the carb kit. The replacement is a convex shape (looks like a lead contact lense), you drop it over the hole and flatten it out with a hammer & punch, or a socket, or any flat round object that fits. It's a soft metal, so it spreads out & seals the hole.
They give you better access to the tiny passages for cleaning, removal is optional.
I use a drill on 'em, a bit of grease on the bit to keep particles out the carb, and don't push through too hard. But, there's enough empty space behind 'em so you don't have to be too timid, either.