When a Eucharistic Prayer is being used which contains an 'epiclesis' later than the Institution Narrative, should the Lord's Body and Blood still be shown for adoration after the Verba Domini?
Yes! Fortescue (The Mass, 1912) explains: "The whole consecration-prayer is one thing, of which the effect is the change of the bread and wine into the body and blood of Christ. During this prayer we ask continually ask for that grace; although the prayer takes time to say and God grants what we ask at one onstant, not necessarily the last instant of the prayer. So in all rites constantly people still ask for what, presumably, they have already received. Our baptism and ordination services furnish obvious parallel examples. The Epiklesis is surely also to be explained in this way ... the Canon is one prayer. Consecration is the answer to that one prayer. It takes place no doubt at the words of institution, but it is the effect of the whole prayer. There is no sequence of time with God. He changes the bread and wine intuitu totius orationis [in consideration of the whole prayer]."
Readers of Catherine Pickstock's After Writing will remember her insistence, in her illuminating exposition of the traditional Roman Rite, on liturgical stammerings and repetitions and rebeginnings, as features of Orality.
In Cardinal Ximenes' edition of the Mozarabic Rite, in which some twenty or so of the 200 Eucharistic Prayers have an epiclesis after the Institution Narrative, the elevations nevertheless always happen at the 'Roman' place.
Ever since 1928, many Anglican liturgical tinkerers have rather liked putting epicleses after the the Institution Narratives. I suspect this is partly the old Anglican weakness for cosying up to what they think of as Orthodoxy, and partly a vandalistic desire to clobber "mechanical" understandings of Consecration. I have known Anglicans who have believed that it is superstitious to think that Consecration is effected by five words, but, for some unexplained reason, enlightened to attribute it to several hundred words.