318 Main Bearing replacement difference.

I have a 1974 Dodge Dart Swinger, factory 318 car with the original 318. I took it out to freshen it up a little. I bought a set of King main bearings # MB55354SI to replace the originals. The bearings I pulled out are original. They have the manufacturing date of "5 74" stamped on the backside. The factory bearings for the # 1 (front) main bearing is a grooved upper half and a smooth bottom (cap) half. The replacement set I bought has 3 grooved bottom (cap) bearings, Rear #5, Thrust # 3, and a third which I'm sure is designed for placement in the # 1 cap.

I have already tried doing research. A lot. I tried to get an answer out of King bearings themselves twice. They just keep sending me a picture of a schematic showing the location of where each should be installed. The won't answer my question as to WHY the front lower is grooved when the factory original is not. They will not answer me if I ask them if it is ok to run it even though the factory setup was a smooth # 1 lower (cap) bearing. So I seek the advice of the professionals on this board who may have experienced the same thing when they took apart an unmolested from the factory 318.

Thanks in advance for any info
~Brian