Hi Tom,
Your steel fitting is the standard for an SSS mast fitted in the middle years of Reedcraft manufacture. Mine is shown in the post at:
http://seahawk-forum.968426.n3.nabble.com/broken-mast-foot-tp4023886p4023887.htmlThat image was taken back in 2004 when I bought "Imagination" (before I changed the name to "Just 17"). There is a slightly longer range shot in the third image down at:
http://www.seahawk17.org.uk/description/rigging.htm#mastHowever, you are talking of the wooden mount. I do not believe this is standard on your vintage of boat. Although a wooden block does appear to have been standard on the later Mistral Craft boat - but they have a different mast, boom and sail plan.
On Reedcraft and Moore built boats I have seen a range sizes and shapes to wooden blocks, which I have always assumed to be retro-fits. My assumption is that they have been fitted by previous owners to allow the mast to swing slightly more to the horizontal when fitting or removing the mast for trailing - and this accounts for the various shapes, sizes, and differences in the quality of wood used. (Typically, river sailors will fit a tabernacle to make passing under low bridges easy. You'll see examples of them at that second link I give above.)
To repeat, the norm for your boat would be to have the mast foot fitted directly to the beam built into the cabin roof.