Just to add a bit of uncertainty to the mix, some of the high water pump 235 and 261 blocks were machined for the locator tabs at the parting line. John's 261 that we built for "Charlie" was that way, and I had ordered the early style main bearings, believing it was a 1954 production block. The casting date indicated 1959, which would have made it a replacement block- - - -early water pump position, and late style main bearings! I ended up drilling divots in the block webs to accept the bearings we had on hand!
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
Love your enemies and drive 'em nuts!