This will be much, much easier and faster to get than on the Xbox One version, as unlike that version, you now get Overcharge for replaying all challenges with a Gold Medal, not just cash.
So instead of maybe getting 1-3 thousand Overcharge every 15 minutes or so of grinding the bridge in the "My Hero" mission, you can get 1000+ each time just doing an easy traversal challenge over and over at a minute or less each time. So you'll be able to buy weapons and the collectible maps much easier. So buy all the weapons you want, and just like the Xbox One version, play the mission "Getting the Band back Together" to level up those weapons really fast. Plus of course since the PC version includes everything, so you'll get the extra DLC weapons and the 4 extra from the weapon pack, though you will have to buy them unlike the One version, where they are just flat out given to you. So you'll be able to pick and choose what weapons you want to level, as they are much more than the 20 or so weapons the Xbox One version had at launch.
I would say Traversal Challenge 14 is the best one to do for Overcharge, as it can be completed in about 15 seconds, and gives 4000 each time.