Have you looked at Pi fonts such as Universal News with Commercial Pi or Universal Greek with Math Pi which were originally from Linotype? Both have standardized prime marks such as you seek. During the days of commercial typesetting they were the standard that just about every commercial shop used with every different type style.

You may already have either of those or a similar Pi font which has prime marks on your system. Check them out.

Thanks! I did look at some of the pi fonts, but ones like you mention and ones like Symbol have prime marks that really don't fit well with a transitional roman... at least not Electra.

I've managed to find TWO fonts that may work, neither of which I own, Arno Pro and Lapis Pro.

I'll have to keep looking...