Back in the day, the one and only on i saw hand half of the exh port cut off then a alu piece was bolted on to fix the exh problem.
Was told that it work GREAT! but was a ***** to keep coolant leak out of the equation.
I can remember that fix.. that short side exh. hump was the water jacket! Then there were the steel flanges that bolted between the head and the exhaust flange that had 'tongues' that stuck into the exh. ports to 'fill' this area.
Let's hope this is the key for IM. People have been working on these port problems for a long time, it takes a lot of work and some special knowledge and ability to understand and visualize the flow to figure these things out.