Not the pump itself, but the tubes it hooks too. The one with AIR in the head has a tube runs alongside of the valve cover, and connects to an injector at each cyl. These are fast burn heads. The chamber where the valves sit is in such a shape, it causes the casting to crack between the valves.
the Other head is a bit thicker in this area
I re read your origonal post, and wonder why you put the new head gasket on?
Did you have the head magnafluxed and trued then, or did you just lap the valves and put it back on the block?
This is a 240 head on my 300. It is a direct swap. I ported and polished it, so it breaths better. Have .020 cut off it, and it raises the compression to 9.5 to 1. You can run high test pump gas.
Did you have anything done to the head? I would at least take it to a machine shop, and have it milled, or belt sanded back to true. It sounds like the head was warped.
You really need to get a set of 87 and newer exhaust manifolds on there. The stock manifold is not very good at flowing exhaust out
I have headers on the carbed 300. it really woke up, but headers are a real PIA. I probably wouldn't do that again