I would lean toward a more durable fix like welding. With cast iron, you can "vee out" along the crack and using nickel stick rod, weld it very nicely. One of the tricks to doing this kind of weld on cast iron is to choose the right heat setting and then peen it often during the process. Any experienced welder will have the knowhow to do it right for you.
There are two schools of thought on the subject. One is to slowly heat the entire casting to a uniform temperature, make the repair and cool slowly at a consistent rate. This allows the piece to expand and contract at the same rate, eliminating stress. The second method involves, as previously mentioned, welding and peening. I would recommend using a air powered needle scaler to do the peening, it is fast and effective. In my experience, the second method has been more practical because I don't have an oven large enough to do the pre and post heating. When welding and peening, I use short welds of no more than 1" at a time and from opposite ends of the crack. I also wait until I can put my bare hand on the weld before making the next pass. I hope that helps, if not you could just bring it on over and I will do it for you...oh yeah, the 2 - 3000 miles might make it a long day! But the offer still stands! Good luck, Brian.
Do You own a car built by Durant? 1926 Model R Coupe
Hi Ken A year or so I was givin a Durant chasis. It has a overhead valve setup I think the manifold is still on the motor. If you are interested I will look