Long ago I decided that my upper cowling will have Skybolt Fasteners, like my RV-7A. They are simply the best!!! Also, I will have the top and bottom edges of the lower cowl also use the Skybolts, but not the aft surface. I drilled out the top hinges while clecoing the spacers to the skin. That was easy. The aft portion of the lower cowl will retain the hinge. Great decision; however upon closer inspection the lower aft hinge extends way past the split line so I had to remove many of the lower hinge rivets so the top 4 inches or so could be cutoff. Not easy, but I got it done by grabbing the top of the hinge with a needle nose, pulling it out away from the fuselage, then grabbing it with a vise grip plier while snipping it off with a metal snipper. That being done I ground the top surface flat as best as I could, sanded it smooth then reclecoed the hinge. I then cleaned up the metal shavings (which were everywhere, despite yards of tape to catch the debris) to get it ready to install the Skybolt flanges.