look, IT WILL NOT WORK! okay? :P levelboss's barely take a 2.5! i have less than 1mm clearence each side (and with my old wheel, the tyre rammed into the chainstay with each kickhop! was a poor build though) and it still did it when i got my HD king axle!
Edit: and why would anyone want a 2.7" rear tyre!? the weight is just stupid, and it feels horrid on the backwheel becuse the tyre has so much rolling resistance, even at high pressure