Help with PITR WAL Restore and configuration.

Hi All,

We are moving to a new backup solution where we will backup direct to the
backup server using a Daily Base backup with pg_start_backup and WAL Log
backups every 4 hours.
In regards to retention we are planning on this.

WAL Logs
Daily 4 to 6 times: 60 days retention.

Base Backup
Daily: Mon-Thursday 7 Day Retention
Weekly: Friday 31 Day Retention
Monthly: Last Day of month: 365 Day Retention

So what I am looking for is some clarification on the Base Backups that are
6 months old for example.
Since my WAL Log backups have a 2 month retention I can do PITR from any
Base Backup + WAL Logs any day from 2 months back.

However let's say for example I want to restore the Base Backup from 6
months ago, I only have the Base Backups.. Will I be able to recover to
that point in time using that Base backup? I have read the PITR
documentation however I still struggle to understand this part of it.

Thanks
Jimmy