Jack Ashford’s story is about how a Philadelphia jazz man ended up in Detroit, playing on hundreds of the greatest R&B recordings ever made.  The percussionist’s unforgettable work with Motown’s Funk Brothers has been oft-chronicled, but on a recent compilation, Ace Records’ Kent imprint has turned its attention to Ashford’s producing and songwriting work away from Hitsville, USA between the years of 1968 and 1977.  Just Productions features 24 sizzling slices of ultra-rare Detroit soul (including six previously unreleased tracks) crafted by Ashford’s company of the same name for the city’s various…