Hello there loki700! I happen to also be someone very interested in Super Mario Kart hacking/disassembly. I would love to get in contact with you and maybe share some notes on the subject! I'm looking to get a team together to disassemble SMK on the scale that SMW and YI have been already on this site. I am passionate about this subject and if you are interested in collaborating, I would be more than happy to accept!
If not, I will still be on the lookout for results screen text so I'll try to keep you updated either way.
Some advice from me personally:
-Use BizHawk's TraceLogger and log to a local file
-Create a TAS or just someway of remotely running a single frame
-Activate the TraceLogger and run it for a single frame when the results text screen loads in, when the results text appears, one frame before each, and one on a different screen as a control, saving each to a different file just in case.
-Locate the differences between each frame and the control, and narrow your search from there, looking at similarities possibly between loading and displaying certain sprites.
-See if any happen to address certain tables and look into those tables (most likely candidates would be lines that use a load indirect addressed by x or y, or load absolute addressed by x or y, as those usually indicate a data table)
Hope I was of some help to you! If you would like to participate in the SMK hacking group, feel free to contact me!
Thanks,
MrL314