The "steam holes" on the 261 serve the same purpose as the ones on a 400 small block V8. They prevent coolant from becoming stagnant and boiling where the siamesed cylinders create a potential hot spot from coolant being unable to circulate between the cylinders. It's entirely possible the undersized hole in the gasket is there to direct more coolant toward the back of the block and less upward flow into the head. The incident I mentioned above on the 302 Ford involved one of my students cutting big holes in the gaskets to match ports in the heads without understanding the gasket was blocking passages at the front of the heads that allowed them to interchange side to side. The result was virtually no coolant flow to 3/4 of the length of the engine on both sides. Smart folks, those gasket designers!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
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