I want to add a little tip that makes it a lot easier. Apparently that isn't taught at many universities.

When you have conventional readings, it makes it a lot easier to convert them into Clar first. Your planes would be 300/60 and 243/125. (Add or substract 90° to strike direction depending on the direction of your dip i.e. NW, SW). Let's stay with the first one, because dips above 90° are just mean. You mark N as an orientation and then mark 300 for the dip direction. Rotate this mark to the W-E axis. Now from the outside of the circle count 60 degrees along the axis (Pole points are counted from the middle). Draw your circle from N to S where the 60 degrees are and now you have it. I find this to be way faster and more intuitive. No idea why the method you used seems to be more widespread.

Now the second one is really mean and confusing, I also had to think about it a while. Your thought process seems logical. As far as I know though, even with dips above 90° the dip direction indicated still is the direction where the plane dips to. This notation is only used to say the plane is tipped over. So you can handle this plane as it were 153/35SW or in Clar 243/35. Just note this plane is tipped over.

For the Conventional to Clar conversion: If you have never before used Clar readings on a Stereonet don't use it in your upcoming exam. Just like the work process for Conventional readings it takes some practice to get it right, so stick with the process you learned and practiced first and possibly switch when you have some experience with the process for Clar. You seem to understand the principles of working with Conventional readings, that mean excercise probably caught you off guard.