[c-nsp] Proper Multicast group assignment for SSM/Source Specific Multicast?

[P C]

When assigning administratively scoped multicast groups for SSM/Source
Specific multicast usage, what is the appropriate range to use?  I know
232.0.0.0/8 is a general SSM range, but is there a subsection that is best
used for "administratively-scoped" or internal-use only addresses?  In the
ASM model, this was typically within different subsections of the 239/8
range.  I can't seem to find this issue addressed in the appropriate RFCs
for SSM.

Additionally, I know Cisco equipment permits the usage of SSM on
non-standard multicast ranges.  Are there any particular drawbacks or
benefits to using SSM methodology on a 239/8 address instead of 232/8?

However, I assume one drawback of me choosing to use a proper 232 SSM
address is it becomes no longer possible to use ASM to the first router with
SSM-mapping converting it to a SSM join.  Is this true?

Thanks!