I've read online that in order to use the old ms1 on a nb miata you have to put a NA CAS, is that still true? Can you get it to work with nb cam/crank sensors?

 

This is a guess. it could be because it may not have the ability to use the OEM trigger wheel on MS1 or it doesn't have the option for Miatas 99-05 spark trigger.If you already have the ECU perhaps you can check the spark trigger options
If you use the CAS you need to use 4G63 spark trigger mode. If there is no Miata 99-05, Miata 99-00 , miata 36-2 options the above is true.

the two sensors or signals are the same on the CAS as we ll as separate sensors on the NB1 you just need to know which ones to connect to the CAS


White is the crank position sensor. Yellow Green? is the cam angle sensor