Although the outside of different boards are about the same size, different makes have different seating and are not interchangeable...

You might have to make (or have made) a custom recessed board, which is not hard to do... A lens board with an oversized hole, a short piece of plastic or paper tube, an another bored out board for the lens inside is a board that can be made
..

I highly suggest looking online for a copy of the B&J catalog from the era of your camera to see if this board was offered as a accessory for this camera...

Failing that, follow Jim's advice by getting a 90mm on a flat board, and selling or holding on to the 75 for another camera...

Note that some folding cameras don't like 75mm's as they don't go too deep inside the body shell, but stick out enough to require them fot the FS to end up between the inner rail and the dropped front rail making it hard or impossible to use on some cameras...

Maybe that's why this lens ended up in a contest... ;-)

Good luck, and have fun!!!

Steve K