Wheel centre bolts.

Unknown

I need some help in locating the carriage bolts
that hold the wheel centre on to the hubs of a 1927 Hudson, that go through
the  wooden spokes.   These should be the same bolts for all
Super Sixes up to 1929, with domed head and share underneath the head, and a
full size shank with machined thread, 3/8" N.C.   The length from
under the head to the end is 2-3/16", with one inch of thread.   The
only bolts we can get here  in New Zealand are Metric, rolled thread with
reduced shank, and are either too big or too small.    Can anyone help
me locate a supply of these bolts?  I would need enough for two cars, that
is 96 bolts.   Many thanks,

Geoff.