I wouldn't use it. With the JB weld you are only going to get a little bit at the end of the clevis attaching it to the control rod. When you properly solder a clevis on to a pushrod the solder will flow down inside the clevis giving a solid and strong joint. The saying "The proper tool for the proper job" comes in to play here. JB weld isn't the proper tool for making up solder clevises. You can pick up a soldering iron for ~$10-$12 at Lowe's or your local Radio Shack. Just make sure you practice making the solder joints before you actually try to solder the actual clevis on to the pushrod.

If you don't have a soldering iron I would go to the LHS and purchase some threaded pushrods and clevises. As an FYI, you can't cut threads in a push rod yourself. The pushrods that you purchase actually have the threads cold rolled into them, so the threads are actually wider than the pushrods themself. If you cut threads into the rod you will find that the clevis won't fit the threads

Ken