Hi, the casting numbers on these heads are 343772. They are large oval port open chamber heads with 2.06/1.72 valves. I want to replace these valves with 2.19/1.88 valves. This engine will go into a vehicle that at most will be driven twice a week on the street and an occasional 1/4 mile run, but I intend for them to be very hard miles on the street. As for the issue of the hei distributor and the tall deck block, i have a weiland team g tall deck oval port intake that i plan on using which will allow me to use a standard height distributor.