Check out Jon "carbking" web site page on carbs by truck year and engine size list for
Chevrolet. Scroll down to the 1965 info and you can see the original Rochester B numbers and the Carter YF model numbers that were meant for your 230. Those model numbers should give you info to search for a carb to fit your needs. In fact a quick web search I did this morning showed some of those carbs being offered by Jon himself. Check out his website and get in touch with him. He will most likely be able to help you out.
If Jon doesn't have one, post an ad in the
Truck Parts Wanted forum.