I just took a look at the SIMTEL arechives on the
Walnut Creek CP/M
disk, and they appear to have all the disks (judging by the directors)
up through volume 310.
There are a couple of entries from a couple of floppies that
were "expurgated" from the SIMTEL archives after some controversy
broke out over the ownership of the files. I think these are
mostly CPMUG things and not SIG/M, but it's been so long that
I cannot remember what the controversy was.
Tim.