Hi there.  I had a look for David Boast but couldn't find him from a quick look-through.  However, some of the muster rolls were difficult to read and I had to guess at names.  Also, I've had to miss some out that were completely illegible.  The men I've listed didn't get promoted up until about 1846 so I'll have another look later at sergeants.  The nearest is Francis Boast but he died in 1841 so it couldn't be him that you're looking for.  I'll take a look at the links you've provided as I know I'll find them really interesting and thanks for posting them. 
Private   1032   Francis Boyd [Boast]   Spent time in hospital, died 1841 aged 23
Private   1112   David Booker   Spent time in hospital, volunteered 31st Foot 1844
Private   1301   David Bright   Spent time in hospital, volunteered 28th Foot 1844
Private      David Brook   Enlisted 1827
Private      David Byers   Spent time in hospital
Cheers
Diana