One other advantage to doing the install of the stock handle yourself is spending the little money you saved on the adjustment part of the system.
My little go-dammit unimaran has the cool adjusters called "trapeze clamcleats". After you slide your new t handle & new oval sleeve up the wire you put the thimble through the hole in the end of the trapeze clamcleat, run your wire through this hole also and around the thimble, cinch it up & "mash" your sleeve with your new toy, er tool, this firmly secures your clamcleat to the end of the trapeze wire. Take a length of your favorite color 1/4" yacht line (double the spec'd length) and tie it to the hole in the bottom end (opposite the thimble) of the cleat using a bowline knot. Thread the end through a dogbone or J&H or whatever then back up to the cleat and thru the only hole left which has a pulley wheel (block) in it. Tie a simple knot in the end of the line, big enough to keep the line from pulling back thru that hole. Install line so the knot is on the side with all the little V cleats. With your trapeze harness on (open part of hook on the front facing down) put the only "free" end of your dogbone or J&H over that hook on your harness. Grab the knotted end of the line (we'll now call it the trapeze adjustment line) and pull straight down. All this should tighten up and you'll feel it supporting your weight, go ahead and pull the line straight into the V's of the cleat and release, it's a one-way cleat. Pull down again to release and raise or lower yourself till comfortable and cleat again. A friend or wife can use it & adjust easily to their liking and you have no work to get it back to your setting. These "trapeze clamcleats" are about $20 each. Some folks will add a block at the "dogbone" end for the line to go through but I like mine without, it's just real clean and simple to use.
I hope none of this sounds as though you don't know anything, just trying to help, because we've all been where you are now at.
and to be honest I really don't understand any of it.