I currently play Diploma level (UK) on a Conn 88H with a Bach 5G mouthpiece
I do a lot of Classical playing with this set up, (attend Junior Conservetoire on a Saturday), and it works very well for me.
More recently, I’ve had opportunity to play an increasing amount of Jazz / Big Band, and love it!
(First chair and plenty of solos now)
The Conn 88H isn’t ideal for this, particularly in the higher registers.
Hence the secondhand Conn 77H

I’d be truly grateful for advice on the best mouthpiece to try with this trombone please?
I’m aware that mouthpieces are ultimately personal preference, but I do need a little guidance on likely suitability and where to start.
From reading through past chats here, the Bach 6.5AL seems to be regularly recommended as a good solid fit for most (so perhaps a good starting point?)
But other comments suggest this is still quite big, and a good intermediate size might be the Bach 7C or Yamaha 48.
(For clarity - I do have a small shank 5G but am aware / advised that this is too big for this model)
Thank you all!