I have noticed at least two styles of Manifold Pressure Sensor (MPS) cans. one style has a long what I call "nose" that sticks out the same end as the vacuum port, the other style has a short "nose".
One person told me that the short nose type will not allow as much adjustment as the long nose type? is this true? and for what applications where the long and short nose types used?

I have two that came from a 2 liter 914 one with short nose, on with long, I have one with a long nose that came from a 1.7 liter.

I want to do some adjustment using an in car oxygen sensor, and wonder which type MPS might be best for tunning.

Not sure about the internal differences between the long and short nosed versions.
The long nose one I checked had an earlier part # than the short nose one I checked.
Can you find the part numbers stamped on the side of the "cover" section?
Most of them have both Bosch and Porsche part #s.
The PB Anders site has a complete listing of part #s and their specific vehicle application