There are several if not many aftermarket head gaskets. And some don’t have as many holes as others. If you have a good look at your head and block, you’ll find several holes that don’t match up. I believe these were for machining purposes and not for anything to flow through. Some gaskets will...
Also, The oil keyholes will sit over the oil hole in the block as well as the head bolt hole between cylinders 4 & 5. This is where the oil passes from oil hole in block to the space around the head bolt and makes its way up to the rocker assembly.
The tab on the one end that protrudes out of the mated parts goes to the rear. When installed, you can check for correctness by viewing or feeling the tab sticking out at the rear of the engine.