Can I put a Tortec Epic rear rack on a 27" frame?
Do you mean this rack? On the linked page it says that the rack will fit a 700c bike. Also I see that there are two holes at the bottom (dropout) mount, that would make it easy to use something like a repair strap to raise the rack if that proves necessary. Use a bolt through both holes so that the repair strap and rack can't move under load.

If you're handy with tools you might find it just as easy to get a short piece of stainless flat bar (or aluminum) and cut and drill it yourself.