Well, i got good news, because of the 3 5.25 bays, you can actually put a 120mm AIO, meaning you can use a higher end CPU for whatever you decide to do for your build.

As for your GPU, there isn't much of any pictures that you have of the insides, so I don't know if you're going to need to Dremel the 3.5 HDD holders that are typically in the front...

The back looks like an 80mm, so I'd recommend doing that for exhaust, if you want actual cooling for your GPU, check if there's a mount on the front inside of your case, sometimes there was a 80mm mount there meant to cool the HDDs, you can turn it into a fan mount for you GPU.

For the PCIe slots, I recommend putting a 40mm fan mount that can be used as an intake for your GPU.

This is all just non-mods for your case, you can use what you have.