All 24 combinations of the letters AEST make a word, from AEST, an obsolete form of 'east' through to TSE-A, a Keresan tribe of New Mexico. The halfway mark has been achieved for AELST (63) and AERST (64), from a possible 120 transposals. These feats are recorded in "Transposing Rates" in the November 1987 Word Ways and the current Colloquy. As far as I am aware, no comprehensive study of six-letter or seven-letter sets has ever been undertaken, but at the next level the remarkable transposability of the eight letters AEGINRST has been recognized by wordsmiths for most of this century.
"The Aeginrst Transposal: Part 1,"
1, Article 2.
Available at: http://digitalcommons.butler.edu/wordways/vol27/iss1/2