Buescher Bari Pivot Screws are longer but I believe they are the same diameter. remember that Buescher pivot screws are straight and not tapered. That means they do not need to bottom out in the key. Unlike the new Bundy screws which are rounded a little at the end, the end of the Buescher Screws are have square edge. This makes bottoming them out in the key even more difficult and impractical. So, length should not matter unless the original screw was bent and wore a larger hole in the key end.
Tapered pivot screws allow a key to be short and worn and still work. Straight pivots force the tech to fit the keys the same as they would any hinge rod keys. You can use a straight pivot that is shorter than the original as long as there is no play in the key and the key fits tight between the post. That said, this is true even when installing the original, correct length, pivot screws on Bueschers.