There is only one lens board (blank) which can be drilled out for several
varieties of lenses.  The more common ones, and which can be bought new/used
are drilled to fit Copal #0 thru #2.  Probably the most "popular" size hole
is 39mm.  I'm pretty sure there is one size board for all Speed, Crown
Graphics, and probably other Graflex cameras.  All boards can be modified by
either enlarging the hole or fitting an adaptor blank drilled for a specific
lens.  Lots of fun, huh?

If all else fails, see Steve Grimes' Co.

Truly, dr bob.

   There are two types of lensboards used on Speed
Graphics. A 4"x4" wooden board, used on Anniversary models
(made up to 1947) and the drawn metal board used on
Pacemaker series Graphics (there is a variation of this used
on the Super Graphic). The real limitation is the size of
the hole in the Graphic front, this may be too small to
accomodate some lenses with very large rear cells. You can
often fit these into the camera by removing the cell and
screwing it back in after the board is on the camera.
  Otherwise the lensboard will take any lens or shutter up
to its size.
  On Pacemaker cameras you may find some shutters or
barrels are too large for the body release lever to clear.
For these (which include the 15" Tele-Optar) the release
paddle must be losened and swung aside.
  Anniversary lens boards are easy to make, Pacemaker
boards are not.
  The 4x4" metal boards made for the Graphic View camera
will also fit the Anniversary camera.

  On second reading. The hole in a lens board can be easily
made larger if necessary. A patch plate with a smaller hole
can also be made, I've done this for Anniversary boards.
Unless you don't ever want to use the current lens again its
best to obtain another lensboard for the new one.

I find lenses that I buy to have such variant hole size
requirements that I simply make my own lensboards for each lens.

Francis A.  Miniter