No. It is not a replacement 109.
For the most part, A stage -1 block is the same as an off-center stage-2 block but without all the holes drilled in it. Also, they normally came with cast 2 bolt mains. If you drill the additional 6 holes for the heads and machine and drill for 4 bolt mains......then you now have an off-center stage -2. Of course, there are variations to this description as well. Like most stage-1's have provisions for an internal oil pick-up. Also you can't convert the #1 or #4 mains to 4 bolt. The part number on the block is usually the same as the stage-2 off center 3.8's or 4.1's.