Yes, I can
From Mid Model Year 1972 until 1975, there were two extra holes drilled in the front of the head, in front of the timing gear. They went into the timing case. It may of been a response to oil leaks.
The problem with these heads is that they were "hardened" so the valves could tolerate the unleaded fuel being introduced. They were not very tolerant to heat, sooooooo if you overheated just once, you were very likely to crack a valve or the head. The earlier style heads were more tolerant to heat.
There are others here who could go into more detail.
HTH
Jeff