That explains part of my problem. My plastic block measure 11.811". I now need to machine down the pads, but which side?

1) Is the crankshaft centered between these pads?
2) My threaded holes are 3/8" course. Should they not be 7/16" course?
3) I now wonder if the threaded holes in my pads are in the correct location. Can you give me a measurement of where the threaded holes are in relation to the front and bottom of the block?

Now that I have this plastic block I my as well make it correct.