Saxophone Journal Vol 19 No. 5 (Mar/April 1995) had an article on Freddie Gregory. Here is an extract:
"A few years ago American saxophonist Bob Ackerman commissioned Freddie to change the key mechanism on two of his Conn saxophones, but Freddie's experience of this kind of conversion goes way back to when he was in Moscow. These days, Freddie has to concentrate on mouthpieces. He does not have time to repair whole saxophones, but his background in repairs has given him a unique understanding of the instrument as a whole."
Saxophone Journal Vol. 21 No. 5 had a CD of Bob Ackerman on "Using Vintage Saxophones in Jazz Improvisation". Track 4 of the CD (according to the insert in the magazine) was:
"The Freddies: A Re-mechanization of 1920s Conns in the Style of the 1960s Selmers. Bob Ackerman plays the Freddie alto Conn #223068 and Freddie tenor Conn #216291 with Wilbur Morris on bass and Denis Charles on drums."
He talks over background playing.
"Many of you have heard of my Freddie saxes. This refers to Freddie Gregory of London's re-mechanisation of a pair of late 20s Chu Berry Conns In the style of MkVIs using some of the Selmer keys . Now Fredddie did a magnificent job. He rotated the left and right hand toneholes to the offset position. Conn developed this in 1932. He did this by cutting the horns in half between G and F - and to quote Mike Brecker "don't try this at home". My feeling was that the 20s brass had a unique resonance. ...... He's a marvellous craftsman in mouthpieces and horns."
Some of the old Saxophone Journal magazines used to have a picture of Bob Ackerman in his advert for Progressive Winds, with him holding the Frediie Conn alto and you can clearly see the Selmer LH pinky cluster and palm keys.
Hope this helps - it takes a brave craftsman to try this !
Rhys