Harley Dyna oil pump

Moin together…. My 95 Dyna Superglide is in the workshop and weakens with the oil pressure. Problem should be old oil pump in combination with slightly tuned engine. I want to know if the statement that the engine for changing the oil pump MUST be removed, true. It is a 5-speed gear without kicker installed and it should be inserted a standard S&S pump. Greeting and thanks