hi el

i don't have a 210, but have a 150 g claron i use as an enlarger lens
... once in a blue moon when i do copy work i put it on my speed graphic.
it is f9 like the one you linked to and isn't the easiest lens to focus.

i imagine you have hopes to use it at infinity ?
from what i remember it is best for that sort of thing
unless you are doing copy work or enlargements / macro work.

if you have your heart set on this particular lens, you might hunt for one
in a barrel, and also hunt for a polaroid tominon type lens in a prontor shutter
there is no machining necessary ( from what i remember ) and you can screw the
elements right into the shutter and figure out your fstops ( measure your iris + divide into your focal length ) .. very easy.
i mention hunting for one because you can probably find one and a separate shutter for a bit less than
that one ....

another you may think about would be a schneider symmar convertible ...
it has huge image circles and the 210 is also a 370 when you remove the front element. it doesn't cost too much and works great with the long bellows
of your 5x7 camera. ( they often go for way-less than 2 lenses. )

i have a 210/370 and can't say anything bad about it ( have been using it since around 1996 )....

good luck !

john