Nope, it was on 235's from about 1956-62 or so. The 261 has a larger combustion chamber and steam holes between the siamesed cylinders. An 848 head can be used to increase the compression on a 261, but it needs the steam holes drilled to work properly.
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!
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