I'm really not sure if 1/2" is far enough in for my liking. I guess I would suggest at least 3/4" to 1".

I use the smaller diameter (1/8")pushrods available at www.darrolcady.com

I'm starting to use these for just about all of my pushrods now. At his prices, you can afford to do this. A 2/56 rod is a slip fit in the 1/8" pushrods. He sells a glue called Black Flash that works great on Carbon Fiber. Its a medium CA type glue with very tiny pieces of Rubber inside. Works Excellent for these types of pushrods. I've also used 20 minute epoxy, which works fine. I've heard alot of people do use the JB Weld so I'm sure you will be fine. Be sure to roughen the metal rod with sand paper and then clean with alcohol or acetone for best adhesion.

The sleeves you mention are a good idea. I have done them with and without sleeves, and not had a problem, but I still think it is a good idea.