I drilled and tapped the head to put in NPT block off caps. The rear hole does not have much material FYI! I used 3/4 NPT on that one and I believe 3/8 NPT on the center one.
I kept the plastic pipe in the block for the coolant overflow, although some day I would like to just make a replacement for the one line. I hate having the other ends capped off because Im afraid of a split in the cap. So far no issues though.
It does make the area much cleaner!!