The answer is always to either get a new bowl or to epoxy over the plugs because there's no way to remove the plugs.

I've taken one out to see what they look like and there's a little O ring in there that leaks for a variety of reasons.

The one in the picture looks pretty good except for the hole I drilled in it to be able to yank it out

Having an extra float bowl or 3 or 4 hanging around, I figured I'd try to get one out without destroying anything.

It turned out to be pretty easy.

To do it , you take an old seat assembly like in the picture below and cut a short rod to slip into it as shown. It should stick out about 1/4 inch. With the seat assembly I used the little rod was about .47 inches long and 3/16 diameter but all seat assemblies aren't the same and a 3/16 rod won't slip into some so you'll have some measuring to do.

Put the rod in as shown and screw the assembly into the bowl and as you do that, the plug is pushed out.

Then you can find the right size O ring and replace the bad one and tap the plug back in place and then you have to peen over the edges of the pot metal bowl a little bit to hold the plug in place.

The edges are peened over from Holley, but when you push the plug out they straighten out, so doing this step is important and necessary to hold the plug in place when there's fuel pump pressure under it trying to push it back out.

The little rod that does all the work

The rod inserted in the seat assembly

Screwed in and ready to push the plug out as you continue screwing the seat in.

The plug laying next to the hole

Here it is all done and peened over slightly

After this was all done, I stuck it on a carburetor and ran it for an hour or so with no leakage.

I shouldn't mention the O ring size because I figure if you want to do this, you can figure out what you need with the old one to compare to, but it needs to be resistant to gasoline and not all O rings are, and you won't be able to blame me if it leaks but something like a 7mm ID X10 mm OD O ring is a good solution  

This only works on the top plugs, I don't think there's any way to get the side plugs out without damage

So is it worth the time and effort?.........that's up to you to decide, epoxy is pretty cheap