Let's simplify this ... A LOT.
The most common disk format (BY FAR) for CP/M was 8-inch, single sided,
single density.
If they are in that format, then virtually any CP/M system with 8" floppy
disk drives can read the disks (assuming that they are still readable). It
is very unlikely to matter what disk controller was used to write the disks,
it is very unlikely to matter what system originally created the disks. The
8" SSSD format is "gold standard interchangeable" among virtually all CP/M
systems with 8" floppy drives. And it was, BY FAR, the most common CP/M
disk format.
Finding a working CP/M system with 8" drives should not be difficult. I
have 3 of them here (I'm in Ohio, USA). There are still many thousands of
running CP/M systems around. A slightly greater problem is getting the
files moved from the 8" CP/M floppy disks to another [more useful] form of
media. What you really want is a system with both 8" and 5.25" floppy
drives, and a PC with 5.25" floppy drives. Such a system would allow you to
move the files from 8" CP/M to DOS/Windows, which is probably the objective.
My experience in reading 8" diskettes written in the 1970's has been
excellent. I have hundreds, probably a couple of thousand such disks, and I
have only had a single-digit number of diskettes that I have been unable to
read out of all of those. Others who have actually had experience with
large numbers of 8" disks also report very high success rates with disks
that have been stored in climate-controlled environments. Now if the disks
were outside in a garage for 20 years, that would be another matter of
course, but for well stored disks, readability is not usually an issue.
It is possible that the disks are not SSSD (single sided, single density),
and if that is the case, then the problem becomes far more complex. Once
you get away from 8" SSSD, there is no standard disk format, rather there
are hundreds of different formats specific to each implementation of CP/M.
This could [greatly] complicate recovery, however, under no circumstances
would this make recovery impossible. CP/M is highly adaptable, and with
some effort (programming) it would be possible, first, to determine the
format, and, second, to adapt any CP/M system to be able to read any disks
for which it had the correct type of drive.
In general, unless the format is ***VERY*** non-standard, it doesn't matter
what the controller was that wrote the disks. Most systems used Western
Digital 17xx controllers, some did use NEC 765 controllers (which existed
for a couple of years before the PC came out), and a few used discreet logic
controllers. But for the most part (and in particular between the WD and
NEC based controllers), disks were interchangeable with regard to being
READ.
A few people mentioned hard-sectored media. While hard sector 8" disk
systems did exist (I have two of them here), it was very, very rare for
hard-sectored media or systems to run CP/M. Invariably, systems using
hard-sector 8" media ran proprietary operating systems. You can assume that
any 8" CP/M system was soft-sectored and be correct at about the 99% level.