Thanks guys for the coments.
Dennis, yes the port repair tool was part of the plan. As this is a small cylinder the grid is 1/4" the way I made the curved port cores it did not leave much room for the gasket to seal the covers.
This is actually a 7/8ths scale Shay cylinder which is why there an extra mounting face. I plan to make a bottle frame engine first for a test.
Here is a photo of the port face, and the mounting face. I was having problems with the mounting face dishing in so I added the samll plate to make that section thinner which is exactly what the Lima Works did and where I got the idea.
The port cores are made from stacked sheet metal. The ports are 0.040" with the exhaust a double thickness and the bridges are 0.050"
The port core block has counter bored screws that act as stops so when the block is pulled out of the wax it only travels far enough to clear the wax model.