Here are some pictures of the real tools. They seem to be available at this website:
http://www.johnsmcintoshvintagemercuryo … Tools.html
One tool they don’t sell is patience. You will need it for this job. If you have that, and enough mechanical skill to do other impellers, you can do it. Just be advised that it’s not going to happen in an afternoon. Don’t get me wrong: The Mark 10, also known as an "automatic transmission" engine, is one of my favorites. I have at least 25 of the type and have done at least as many impellers. It still takes me a long time to do it right.
One thing I don’t show in these pictures is my trick for cleaning out the area where the water pump cartridge resides. I have two small wire wheels that fit in an electric drill. One is a side wheel and one is an end cut brush. I chuck these into a 12" drill extension, to clean all the corrosion and gunk out of the drive shaft housing cavity where the pump goes. This makes things a lot easier to put back together, without force or cuss words.
Long live American manufacturing!