I bought and have used one of Jim's drill guides for the OS 35-40 FP and LA 46. It cost $22 plus $4 shipping. As is typical of Jim's products it is well thought out and beautifully made. Delivery was very quick. I find it very useful and recommend it to anyone who, as I do, needs all the help he can get in drilling accurate mounting holes.
I have discovered that the drill guide for the 40 FP, etc., matches the mounting hole pattern for the Brodak 40 and for the Magnum 40 GP as well.
In addition to using the drill guide to accurately locate mounting holes I intend to use it as part of a jig for constructing engine crutches. I will, however, have to measure the case width on the Brodak 40 and the Magnum 40 GP to determine whether the drill guide can be used as is in making crutches for those engines.