Transforming the .bib file to get upper cases

of course, this isn't an answer to "how do i modify my .bib file"...

make a "myplain.bst" that is a copy of plain.bst, but replaces

FUNCTION {format.title}
{ title empty$
    { "" }
    { title "t" change.case$ }
  if$
}

by

FUNCTION {format.title}
{ title empty$
    { "" }
    { title }
  if$
}

and then change your document to use myplain.bst instead of plain.bst

do not, under any circumstances, change your plain.bst file! ... changing a fundamental part of the distribution will lead to tears, later.