postgres for production - Mailing list pgsql-admin

I have a question for postgres hardware requirement for production installation. My org want to use Vms with only 8 cores max + 64Gb RAM max. I have 4 database out of which 1 Db is write extensive 1 db is read extensive and moderate write and 2 other DBs are read with write one. 

can someone suggest me is this a good configuration with respect to hardware ?

Thanks in Advance.
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