The only cartridges that can replace the PGBK 220 are the PGBK 226, PGBK 520 and PGBK 526, but both the PGBK 226/PGBK 526 are Opaque.
You can use any of these cartridges as a replacement for your PGBK 220 but your must swap the chip from your current cartridge to make them acceptable to your MX870..