I don't know about fees etc (ring them on +298-332228 or check
www.slv.dk/vagar ) but Westray overhead to Vagar is 12nm lwss than Sumburgh to Vagar. At 120kts still air is 1:53. Why not depart from Kirkwall and save the trek to the Shetlands.
Edit to say that the link is down. It does not even work from the slv website. e-mail address appears to be
[email protected]