The basic design is OK. The sweat shield, as drawn, will interfere with getting a firing grip on the draw. You need to trim the back edge some. To judge where your belt slots will go you need to draw on an accurate stitchline. This would be one half of the weapon thickness + one thickness of leather from the profile of the weapon. Once that is established you can locate the belt slots. I find that 5/8 of an inch from the closest part of the stitchline works well for most handguns.