Fuse68 is a 20 amp fuse. It is hot all of the time. Because the fuse blow happens after the key is turned on, the issue is not before the ignition switch but after it. F68 feeds your keyed ignition switch assembly. So the fuse could be blown by several scenarios.
1.) key accessory position
2.) key run (engine off position)
3.)key start position
To better help you will need to determine which of these scenarios causes the fuse to blow. One way to do this would be to remove the FUSE 68 and place a probe on the spade connection that runs to the ignition switch, not the power input side of the fuse. Do this with the key turned off. You may also wish to disconnect the battery for added safety.
You may wish to begin this with the key in accessory position. Not sure if loss of power to the ignition switch causes it to lock and stay in the ignition with loss of power via F68. Use a volt/ohm meter and check reisistance from the fuse socket that feedsthe ignition switch (light green with violet striped wire) and chassis ground. You are looking for less than 1.0 ohms resistance which will indicate a short to ground. Cycle the key switch until this is found. Then report back if you need assistance. This is the first way to begin dividing and conquering a chart to ground problem if backtracking your work and luckily finding a mashed wire.
here and willing to work through the schematics with you if you need me.