That is simply a baffle that prevents oil from being drawn out of the valve valley by th road draft tube when the vehiclre is in motion. A little creativity with a torch and some exhaust tubing can duplicate it pretty easily. Find a piece of tubing that is a dnug fiy into the hole in the block, and favricate an outer shield from a slightly larger piece of tubing and some big flat washers. Then drill a few holes near the top to allow vapors to be drawn out of the crankcase by the air passing by the end of the draft tube. The same vewnt system was used on 283 and early 327 engines until the mid-1960's, ao an exact replacementy shouldn't be impossible to find.
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!