You're allowed some latitude and not every engine builder follows the same routine. Generally, all ring gaps are located in the diagonal regions situated between the wrist pin and the piston skirts. The orientation to avoid is gaps, especially adjacent gaps, approximately aligned.
As a rule of thumb, the upper and lower oil ring gaps are spaced 180° apart, each ~40° from the wrist pin axis. The first and second compression ring gaps also are spaced 180° apart, each ~40° from the wrist pin axis. An imaginary line drawn to intersect the oil ring gaps will form a flattened “X” with an imaginary line drawn to intersect the compression ring gaps. So, looking down on the crown of a piston with the wrist pin horizontal and the circumference of the piston crown divided into 360° clockwise from top center, orient the top compression ring gap at ~50°, the second compression ring gap at ~230°, the top oil ring gap at ~130°, and the bottom oil ring gap at ~310°.
The reason some engine builders orient ring gaps opposed from bank-to-bank is that an engine always rotates in the same direction. Since the rotating assembly changes the linear motion of the piston into rotational motion of the crankshaft, the piston rod constantly changes its angle with the piston as the crankshaft spins. On the upstroke, the rod thrusts the piston toward one skirt into its adjacent cylinder wall. On the downstroke, the rod forces the piston toward the opposite skirt into its adjacent cylinder wall. The greatest side thrust is applied to a piston skirt and cylinder wall during the power stroke. The major thrust skirt of a piston is always the side of the piston that is opposite the direction of crankshaft rotation. Hence, the major piston skirt thrust on one cylinder bank occurs on the opposite cylinder wall compared to the major piston skirt thrust on the opposed cylinder bank. For example, if an engine rotates CW, the piston major thrust skirt is on the left side of the piston looking down the crankshaft axis as the crankshaft rotates. A SBC engine rotates CW from the perspective of an observer looking at the engine from in front of the crankshaft. Major piston thrust occurs on the upper wall of a cylinder located on the driver side of the engine and on the lower wall of a cylinder located on the passenger side of the engine. The feeling is that the resultant piston rocking can impact ring sealing, thus, gaps are oriented accordingly. However, fretting over such nuances with regard to daily drivers is splitting very fine hair. It is unlikely that you would notice any difference or improvement either way unless the engine is clearanced and runs notably loose.
Didn’t you state previously that you have a machinist/engine builder you trust? Ask his opinion. Just, don’t be surprised if he differs.
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