If you drive at all in the winter here in Kansas, you need the heat riser. I ran my 216 for the first winter without one, the truck was a terrible runner until it warmed up and I had to choke the devil out of it.
As for split manifolds, it's tough to go wrong with cast Fentons or the Kansas Kustoms. I have looked at the KK work, and they do an excellent job, plus you get to use the heat riser. The shaft hole can be bushed.
