You can make up (or maybe buy) a union that reverses 3/4” male to a female (3/4” coupler) and then have 2x hep2o manifolds to the same thing, so the first facing up, and the second facing down; the hep units link male > female, and sit in the same direction, hence you’d need to rectify that so you could go male > male or female > female, whichever works better.
Obvs you’d have an issue creating the looped feed to both ends, but tbh with good pressure and no 28mm pipework, I doubt there’s any need to create the looped feed.
or
which will allow you to flip the second one 180°