Originally the valve seats were cut in the top of the barrel. Over the years, continual re-cutting/grinding can cause the seat to sink down. Your engineer should know that the new insert will be flush with the top of the barrel and a 45 degree seat cut into it.
I don't think you would need to give him any instructions, but he will also need the valves. Ron
Also ensure the finished exhaust valve seat has a minimum contact width with the valve of .125" (1/8")...The relatively wide seat helps to transfer heat from the valve head to the barrel....Ian
