Hmm. Having never seen a Premo Long Focus I went looking for images of one, found this: http://www.thepriceguide.com.au/inde...era-wood-case/

The image doesn't make it perfectly clear whether the board is detachable, but it seems to be. If so, many modern 210/5.6 lenses are in #1 shutters. The #1 goes in a 39 mm hole and a #1 Copal's outer diameter is 73 mm.

Putting a lens in #1 on the beast should be possible, will require a new board or boring a larger hole in the one you have. What have I missed?