dont think they had the holes in the heads
I think the airpump pumped it into the manny in it own passage then mixed fresh air with the exhast on the way out
that was mopars way of deluting the exhast with fresh air to lower emission at the tail pipe/sniffer
i do know most of the SB that have injection holes are most times pluged from carbon anyways
only had one that leaked with headers when I did not plug them
so I just drilled tapped the one hole
but after the rebuild and VJ,they were all open but the one pluged hole