Yes ss21 orange, magenta,orange,cyan,lbk,yellow,Lmg,bk,LcyanIf I orange ink set up you mean you're equipped with orange SS 21 , I would be more concerned with toggling the ink values than I would with RGB in prepress.
This is in rasterlink? ThanksOpen special color book under the tool tab and toggle your ink % in steps for a reference, this will without a doubt get you were you want quicker than adjusting and re ripping updated files with rgb, just export in swop or (working cmyk) from wherever you design and try using spot colors to replace from the values on your target.