Looking at the Kohler website, they say that you do not have to replace the existing trim plate or valve in order to install the hydro-rail. I'm a little confused. Is your problem that you want/need to match finishes exactly with the existing trim plate?? Also, replacing a trim plate doesn't necessary mean you have to also replace the valve. If it is not possible to replace the Delta plate with a Kohler plate (perhaps because of the screw hole pattern on the valve) there are a lot of companies online that sell what I call "knock-off" trim plates that can accommodate your screw hole pattern and they usually offer them a variety of different finishes. Recently, I installed a new brushed nickel shower head. The old one was chrome and so was the old trim plate. Since I had to keep my existing valve...and because Moen did not offer a brushed nickel trim plate to fit my existing valve, I went online and found a company toolboxsupply.com that offered a Moen-looking plate in brushed nickel that fit my valve perfectly.