@Tom P, these are plastic floats, I do not know if they are solid or not but they are really light with no noise in them.

It can be soldered.
I would measure the diameter, I'm sure you could source a bit of brass tube easily to replace it.
Shouldn't be too difficult to remove, but I'd source the replacement before trying.

If they're plastic floats you're probably fine, mine are brass.

You should be able to solder that, but it looks like there's another crack at the very bottom toward the left. Use flux, and just make it as neat as possible. Maybe test it out before you put everything back together, and make sure you don't fill up the tube with solder

It looks like is is cast in with the bottom. Another note, the close up shows something I did not see before, a possible crack from the overflow to the cast lug in the bowl bottom.

Update
I went back and looked at the crack in the bowl, I cleaned the paint off the outside and found that the crack is all the way through... Sounds like a new bowl is in order, or an all new carb....

@ Tom P, I just noticed the potential crack too.

How does this happen????

I wonder if using J-B Weld would be another option? Solder can be tricky to get it to stick to the aluminum bowl, but J-B Weld would, so you could seal the Joint between the brass & aluminum really well.

 Actually what Pete said is the best idea. Just use those HF digital calipers you had in one picture to measure the tube OD, and go to a hobby store to see if you can find some tubing to match it. If you solder, J-B Weld or use heat shrink tubing, it's probably going to eventually leak again. To remove it, just heat up the bottom of the bowl so the aluminum expands, and it should pull out.

I like the idea about the tube replacement, the expanding the aluminum. I will look up what it takes to solder aluminum. I found an NOS bowl on ebay for 79 bucks. I will get a new cab first, if available before I get that, since this carb may not be finished surprising me.

Well there ya go MarkT nails it & i've never seen that happen before. Infact what would cause that tube to split. Can ya pull the tube out & bung the hole or cap the outlet under the bowl. Or simply leave it in place & cap or solder the outlet. Then you have to hope it doesn't flood but chances are you have it right & float level about square on. Carb has a breather or one eack side op on the side so i wouldn't worry about that. Yep just solder the outlet & ride on into the dessert. Think you mentioned soldering alluminium. I didn't think that was possible [or is it--things to learn].

After 3 attempts I got the overflow problem fixed. It was difficult finding the right solder to do the job, could not find acid flux, but found acid core solder which finally got the job done.

  



The pic of the repair is crappy, but I hope it shows well enough.