Sousaphone neck question

[Ernieball]

Hi folks
It looks like my Sousaphone neck has the red rot... It still plays OK but I'm guessing its days are numbered so I'm looking into a replacement.

I'm told that she's a replica of the Conn 20K, made by (or for) 'German Brass' who no longer make instruments apparently.

Does anyone have the dimensions of a Conn 20K neck please?
I couldn't find anything on the internet.

I'm in the UK, so buying a neck that doesn't fit from the USA would be a time-consuming and costly mistake that I'm keen to avoid!

If anyone has a decent one for sale, I'm interested!

Also, if anyone has any advice on dealing with red rot, it'd be appreciated

Thanks in advance

EDIT: Photo here https://imgur.com/gallery/EcdZo

[Dan Schultz]

I agree with Bloke. I don't see a red rot problem with your current neck. However... I've attached a page from the Allied Catalog so you can see what's available.