Keith, there was a .35 X Blue ribbon special. Essentially the engine came with dual needle bearings front and rear. I can't exactly see the nose of your engine. The .35X afterwards came equipped with a single rear needle and bushed front. The later .35X also came with gussets in the case bottom to the shaft area and the front lugs of the engine mounts also had triangulated gussets. The Blue Ribbon offering was fairly short lived. I'm pretty confident your engine is the Blue Ribbon engine. The engine was offered at a special price to entice buyers.
Just to add, I don't believe the backplate was equipped with a pressure nipple.