Just to make sure I'm understanding correctly:
You bought a .40 upper, then got a conversion barrel to make it 9mm, then put that on a 9mm gun?
Why not save the intermediate step and get a G34 slide?
I got the lone wolf 35 slide from someone for $200, it was brand new and never used. Came with sights and an OEM Glock 35 barrel.
To each his own I guess. They're $175 new and naked. Since you changed out the barrel right away, I wouldn't consider that a gain.
I've just been looking into this option to put together a limited major gun on my g34 frame.