Peter,
I don't know exactly what the oil pump cover is on my car - it was sourced by the guy who rebuilt the engine. He was/is an expert on the Chrysler B/RB engines and sourced most parts from the US. I just know it's a Melling M-63HV pump, although that's very similar to a standard pump.
My pump cover has two front facing ports like the Milodon cover, but I don't know if it has another inlet at the rear. The car isn't very accessible at the moment - I will check when I can.
I'm fairly certain that the third port is for use with a dry sump set up.
I have since found a discussion thread on a Mopar forum where they discuss this;
https://board.moparts.org/ubbthreads...2660464/1.html
Here are the two relevant posts;
Thread title: Remote oil filter adapter for BB pump
Question:
"I am using the internal oil pickup. I only need to have the fittings on the pump for the remote filter. These pump covers that include both the remote filter fittings, and the external oil pickup lines, can I just plug the pickup line holes?
Will they then work with the internal oil pickup passages (stock/hemi)?
For example, the Milidon-21225"
Answer:
"There shouldn't be any issues if you wanted to plug off the external pickup line and just use your existing internal setup, as long as you use the same pump. Some of the race pumps don't have holes drilled for internal pickup."
However, if Bristol has an original one presumably that's cheaper that buying the Milodon product?
Although the Milodon one is probably less likely to fail than the original one.