For a stock agency, ProRes or DNxHR are probably your best codecs. You could either add the customizations to the ProRes preset as described in your other post, or you could wait until the next version of Shotcut which has those changes already built into the preset.
If you wanted to go the H.264 or HEVC route, the post below has some specific values you could use. However, you would probably have to change the Other tab to set pix_fmt=yuv422p because many stock agencies prefer 4:2:2 over 4:2:0 video. EDIT: Now that I think about it, I’m not sure if the H.264 presets adapt to the pixel format of the input video. I’ve always forced the pix_fmt option to guarantee I get the format I need.