Take the pump info including make, model, serial number, impeller cut (dia.), rated head, and rated flow Flowserve. The picture of the nameplate you posted might even suffice. Ask them for a curve. It's worth a shot even if they no longer produce that pump.
Suggest you try a few companies who resell and supply pump to customers,
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)