if you cut it yourself
make sure you cut it a tiny bit
narrower and shorter than the actual size
( by about 1/32 to 1/16" )
while the format suggests it is the actual size of the film
it is not, it is the size of what the PLATE was ( dry plate ).
when film came into vogue people bought septums to convert their plate holders
to use film, they were a little smaller than the plate size to fit into the holder ...
and eventually when people bought actual FILM holders instead of plate holders,
the manufacturers didn't bother to change the size of the film, and holders, since people were
still shooting on glass during the same period ...
good luck finding your film ..
john