I would like to try it someday, but I had some really bad trips on dissociative drugs in the past, and I'm worried ketamine will invoke flashbacks.
I've taken care of multiple ketamie and MDMA overdoses (in the sense of unexpected effects, not just the amount) and they did not have a good time. (I also know plenty of people that had a blast on the combo, my point is: don't recommend drugs or combos easily.)
The main thing to remember is that combining drugs means taking less of each than when you take them by themselves. As always in all drug use: Dosage, dosage, dosage.
Overdose can mean multiple things, the one you’re referring to is the medicinal overdose with danger to health, and what most people are (exclusively) familiar with. An overdose in the psychological sense is anything that exceeds the desired effect. Someone who wanted to party and quietly sits on a log, occasionally vomiting, unable to stand up, afraid to die, is definitely an overdose in the psychological sense, even without medicinal danger (regular breathing, responding to stimuli, effects stable). The transition from »oops this is too much, oh well« to an overdose is a spectrum.
Psychonautwiki is a very good source, but neither it nor scientific literature has a good overview over individual cases. I know I’m at the base of the pyramid of evidence talking about my work on festivals doing psycare, so even if you doubt the stories me, my colleagues and any techno scene paramedic could tell you, the most important point stands: do not recommend drugs or even combinations to people without medical background. (For that, I can give you papers on e.g. people metabolizing MDMA via the MDA route exclusively for dramatically altered effects.)