Based on the photos, certainly the proximity of the OD to the chamber wall is too tight with the 194 head, and no flow around that area will occur until lift is fairly high.
However, how many differences between the castings are known as to where is the water, wall thickness, etc.?
The plug location and angle appear to differ significantly between the 292 and 194 heads; how much iron can be cut back toward the plug thread on the 194 before you get wet? In short, can be wall be moved back as far as is the 292?
The advantage is that this area will have lower volume after cutting, and can be made the "heart" shape with less work.
