Lucky you, that you mill one out. Us bottom of the barrel Shade-Tree-Mechanics use plumbing fittings.
722.5 transmission oil pump rebuid DIY - Mercedes-Benz Forum
Here is mine from a PVC coupling next to B1 and B2 piston. The hard part to remove is the B1 piston and install.
I suggest use get the updated EPC data for your vin as most of us here in the USA have. Here is what it looks like, and this is to my S320 with a 722.5(post 13):
http://www.peachparts.com/shopforum/tech-help/321329-722-5-tear-down-side-start.html
About your scored B1, look for a junk yard for junk transmission, FleaBay, CraigsList, or these guys:
MBZ 722.3xx
Do replace B1 because you will just eat-up the bearing in a period of time.
I do not know who's rebuild kit you are going to use, but nearly all aftermarket kits include all the seals for the valve body. You can get an American Rebuild kit with clutches for $180 USD.
I have lots of data on these transmissions if you need something let me know.
Best of luck,
Martin