That is the oil distributor tube. it passes through the water jacket and exits the block on the passenger's side under the pushrod cover. It cannot be removed without damaging or destroying the tube since it's either crimped or soldered into place. The tube supplies lubrication oil to the rocker arms under the valve cover. If you want to remove it for some reason, cut the tube off near the block on both ends and thread a piece of stiff wire through it to assist in the installation of a new tube. Most of the resto-ripoff places sell a kit to replace the tube, with all the fittings needed to do the job properly. Use ONLY copper tubing. Steel brake line material will rust out and you'll end up with a coolant/oil intermix.
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!