Without seeing the engine, I can't advise you about what you need. I've been fabricating appropriate parts for special applications so long that it never occurs to me not to just make something fit that's probably better than original. baffled high-capacity oil pans with special pickups for round track racers, for instance.
Why are you changing pumps? Is the original one that fits worn out or damaged? In 60+ years of engine building, I've seen fewer than 10 oil pumps that actually needed to be replaced. Most of them were badly scored from ingesting metallic debris.
Jerry
