Hello.. It depends on which teleflex you have, but should not have to redrill anything. Just remove steering wheel & bezel and mounting bolts and flip helm., then rebolt cable to housing. Here is link to instruction manuals for installation, just choose the correct one you have.
http://www.teleflexmarine.com/cgi-bin/library.cgi?site=home&type=us&library=1018
Marine Mechanic
Certified Technician Mercruiser Mariner Mercury Johnson Evinrude & business owner