ANSI B73.1 is a dimensional standard not a pump performance standard, and you are correct, it doesn't cover self-priming pumps.
To my knowledge there is no standard of any type for self-priming pumps, either dimensional or performance.
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.)