I wouldn't worry about the stock cam bearing installed correctly affecting oil pressure, your block doesn't have any oil passages in it going up to the top of the block now, correct? Even if it did I wouldn't worry about, you can turn the cam bearing about 120 degrees to use one of the rocker arm oiling passages only to oil the cam
l have made the mistake of trying to limit oil to the camshaft by turning the cam bearings so only 1/3 of the stock oil holes was expose to the cam in the past, not worth doing in my opinion now