Bill, 

Pardon the huge snips of your findings for the moment, but I'll answer your
questions and post a little bit more in response to your interesting research
...

> As Adam said, Perth Scotland.  That the iron is marked "Malloch & Son" (you
sure there's an S at the end?) means it was made between 1891-1911.  It *could*
have been made in 1878 during the first "& Son" incorporation.

1 --  after giving the iron an Evaporust bath overnight it was much easier to
read the now crisp stamping without interference from paint, rust and
indeterminate gunk.  'David Malloch & Son' is in an arc above 'Perth'

> Were there no markings on the plane body?
2 --  well, yes there were.  Two groups of markings.  Owner AW Wallace
apparently didn't want to leave much opportunity for anyone to swipe his plane
and restamp it with their name, whacking clear, crisp impressions of his own
name twice on the toe and twice on the heel.  He was polite enough at the toe to
mark it a fair distance below the other stamp.  That is a clear, crisp stamping
of D Malloch & Son (in a pent-roof shape), above 'Perth', with the entirety of
that stamp inverted (unless you are reading it while holding the plane bottom
side up)

> Here's another 90deg. bedded toothing plane by Malloch at Jim Bode's:  
and here at Ontario Antique Tools:   The latter shows it as an "& Son"
plane without the body being marked "Perth Plane Works" (as I would expect it
would be were it made there), so between 1878-1903.

3 --  What I find interesting in comparing the example here to those two images
is the difference in the shape of the wedges -- This plane's wedge is a dead
ringer for the wedge in my Atkin toothing plane, meaning the large lump that
constitutes the upper part of the wedge in the two images you found is perhaps
triple the mass of the upper part of this plane's wedge.  Seems likely this
wedge is from another plane.  Not all that surprising for a plane that is almost
certainly 120, and might be 140 years old and had the audacity to escape the
Wallace family despite AW's efforts at loss prevention.

Other updates -- ten minutes at the grinder and the iron now has functional and
effective teeth.  Now I just need to skim the sole to remove dragged globs of
paint and shallow scratches before I wax it and put this plane to work.

Yes, this one will again be used as at least one of the Mallochs, possibly the
younger one, had intended.

Thanks, guys!   
Charlie Driggs