Identifying Excitatory and Inhibitory neurons in wild type data

[cspurandare]

Hello,
I am playing around with the data from wild type mice, and I want to separate the single units recorded into pyramidal/excitatory vs inter neurons/inhibitory. I have tried using the waveform duration and half width parameters, but they do not seem to lend a clear separation, even after combining them with mean firing rate(basically using a scatter plot). Is there a well tested way of doing this? I can imagine the use of cre-line data where Parv/Sst/VIP interneurons would be labeled, but I would prefer to stick with wild type mice data for now.
Thanks