I made a pattern and had the dividers cast a long time ago.
You could take tin and make a wing shape in the valve pocket it would look like a Y from the top view this would help register it in the port.
If you have a lump in your head just take a thin 1/16 scrap of metal, after the head is installed shape it to the port and let the plug at the top of the old bolt boss hold it in place maybe put a tang that registers in the allen head. You could even let it stick out of the port and extend into the manifold. Anything will help it's just the better the seal the better it will work.
