The pressure fitting at the front was a leftover from the 1955 265, which did not have a full flow oil filter. The input line to the bypass filter attached there. In 56, the filter canister mount was incorporated in the driver's side rear of the block and the front oil port was plugged. Eventually, that port was not drilled and tapped. I used to drill and tap that hole for a pressure warning light on the race engines, since it's at the very end of the pressurized oil passages. We set the idiot light switch at 20 PSI so the driver had time to shut down before serious damage in case of an oil pump failure, etc.
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!