You need to process the image in ACR and then read them in Photoshop.
If you have a Mac you can use the OS's DigitalColor Meter while in DNG Profile Editor. I use it when running the Fors and Tindeman calibration scripts.
The numbers shown by the PE do not reflect the output Lab values, only the input Lab values. Therefore, at present they are not useful for doing comparisons against published reference numbers.
My suggestion: go by the visual color results, not by the numbers you see.
With all due respect, if the numbers shown by the Profile Editor do not reflect the output values, only the input values, then this aspect is a farce and useless. It would take untold number of hours to produce a decent profile. I will, as I have in the past, use my own hybrid method of HSB adjustments with Lightroom as the front end.