Hi Lee,
As far as I can tell 1K0 953 549 AF supered to 1K0 953 549 AK > 1K0 953 549 BK
That aligns with this page:
.ross-tech.com
The alternative BP control unit you plan on purchasing and installing has a note:
#2: Manual Transmission only, does NOT support Ignition Key Lock.
I would play it safe and get the direct replacement of 1K0 953 549 BK but if this is a manual transmission car you should be OK.
Either way, you will want to save a
complete Auto-Scan with the old unit installed so the factory Coding is saved. That makes coding the replacement unit significantly easier after installing it.