determining max_fsm_pages

Pg: 7.4.5
8G ram
200G RAID5

I have my  fsm set as such:
max_fsm_pages = 300000          # min max_fsm_relations*16, 6 bytes each
max_fsm_relations = 500         # min 100, ~50 bytes each


I just did a vacuum full on one table and saw this result:
INFO:  analyzing "cdm.cdm_fed_agg_purch"
INFO:  "cdm_fed_agg_purch": 667815 pages, 3000 rows sampled, 52089570
estimated total rows


My question is this:  I have about 8 databases running on this server.
When I do a vacuum full on each of these databases, there is a INFO
section that I assume is the total pages used for that database.  Should
add ALL these individual pages together and pad the total and use this
as my new max_fsm_pages?  Should I do the same thing with max_fsm_relations?

TIA
Patrick