Unknown oil fitting? Options

[lmcchesney]

I put the engine back in and cranked it over following the rebuild. I found significant oil leaking/draining from behind the impeller housing. I ended up pulling the enginen out and looked at the source, thinking I did not get the oil in and out barbed fittings tight. To my suprise, I found a fitting hole which I cannot remember what its purpose is. I believe this to be the source of oil loss.
This is a modified 2.0L. We run an external oil cooler in series with our stock oil cooler. Denny removed the stock oil filter mount and capped it off with a plate. He plumbed the case for _8 fittings for oil in and out to the external oil cooler and remote mounted oil filter.

[groot]

I'm using a remote oil cooler adapter that I really don't like. It sends the oil lines straight up from the old cooler location and they interfere with rotating the distributor to time the engine.

I see the solutions posted here and I'm intrigued. A simple blockoff plate for the oil filter is nice, can I do the same for the stock cooler?

Also, it looks like you gentlemen have NPT fittings in the front of the block. Did you tap these yourself or are they already there? I didn't look real close at that area when the engine was out.