I can attest to this as my L31 has the same 4x ring and I will occasionally get random misfire counts. I have a aftermarket Accel billet aluminum distributor from back in the day and I replaced the poppet injector assembly with the revised Multec 2 assembly.
Usually no misfires, occasionally and randomly, a misfire. No codes set, just watching it on a scanner. I don't lose sleep over it.
Just about any Snap-on scan tool will do. But I do have a original Hewlett Packard Tech 2 that I bought in 1999 through the Cadillac dealer I worked for.