You must put the dowels in as it aligns the rear bearings to the input and pinion shafts , the originals are short I used alloy tube as it was a perfect size 10 or 12 mm from memory.
John I have a dxf at work for the plate if the others posted are no good.
I was getting them made thicker say 12mm then getting it surface ground to 10mm, or 10mm ground to 7 this is all of memory as I dont have the info in front of me.
Jim