People drill into the wheel center not the rim itself. Get rid of the original wheels or you'll be chasing wheel covers forever. Hub caps are different animals. They only cover the hub, like Baby Moons.
New wheels solve the sidewall flex problem because the rim of the wheel is thicker. That makes the wheel covers tougher to install because the ID of the rim is slightly smaller. but they grab better. Also, you need all-metal valve stems covered by a piece of fuel line to act as a separator between the wheel cover and the stem. If you use rubber stems your looking for a trip with roadside assistance. The wheel covers creep, bending the rubber valve stem over so hard they break, or pop a wheel cover. New wheels are inexpensive compared to a wheel cover. I wouldn't drill a hole in a Mark II cover if I didn't have to, and you don't. I used to lose my covers all the time. Only lost one in 15,000 miles, and that was my fault for letting the tire shop use stick-on-weights that were too wide.
Do a search. We've discussed this many times. People that go with my suggestion are quite pleased.
FYI, there are better choices than Coker.
Barry Wolk
Farmington Hills, MI
C5681126