Your 1955 261 will need two holes drilled and tapped for 3/8" pipe fittings, and one internal passageway in the block will need to be plugged. Then any of the remote oil filter adapters for a spin-on filter can be plumbed into the oil circuit between the pump output and the block. That type of filter will strain out the rocks, marbles, and bowling balls that could damage the bearings. Detergents and dispersants in modern oil should prevent the sludge buildup that gives some people on this site a case of the vapors. Sludge buildup was mostly the result of running non-detergent oil way past its normal change interval.
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!