theres a fobco motor mount on fleebay at the moment don't know it's the same as yours i could measure mineBrilliant Job on the on the Fobco Atconut.
Just bought an Elliot Progress and intend to do a similar job on it.
Problem: Mine has the motor mounting plate missing along with the motor.
Motor not a problem but would love to locate a mounting plate as they are a cast plate like the Fobco.
Not in my remit to manufacture one.
that would look great in my workshopa bit bigger picView attachment 91924