For once, I find myself agreeing with Ken ... IMHO Dusty is/was way overrated as a vocalist. Take her supposedly classic Dusty in Memphis LP, every track on that LP was a cover and every one of them had - either before or after her - been done in superior style by, dare I say it, "authentic" US soul artists . The LP's reputation had more to do with Jerry Wexler's production suss and the fact that she had become the darling token "white girl who could sing soul" of rock music critics of the time, a bit like a softer version of Janis Joplin. Actually , the Dusty in Memphis LP was a commercial failure at the time , barely scraped into the charts , the general record buying public just didn't buy it ... and of course Aretha , Gladys Knight and most of the other truly great female soul artists were deservedly selling records in bucketloads at the time ....
And her LP in Philly with tracks such as Silly Silly Fool WAS admittedly a very good one, probably her best work, but it was more a testament to Gamble & Huff's writing and production talent than Dusty's vocal treatment.
Yes, Dusty's version of What's It Gonna Be IS superior to the original by Laura Greene but again , it's the great backing track that is the star rather than Dusty and I also believe that the backing track was recorded in the US with Garry Sherman , who was of course Jerry Ragavoy's production cohort, and Garry Sherman could make ANYONE sound good !!!!
Sorry , the best I can say is that Dusty was occasionally pretty good , but of the other UK females Cilla Black , Lulu and Helen Shapiro had greater vocal talent if we are all being honest , and then you have others like Julie Driscoll who were truly brilliant ...