Toilet siphon, does size matter?

[swoop]

I'm new to this forum, perhaps someone can advise. My current Dudley Turbo flush has the white column (siphon) at 8 inches tall. The cistern will probably take a 9 inch one. I have been offered one with a shorter siphon 7 inch or less. Will this work perfectly? I can guess the link to the lever handle may not be long enough, but will it flush properly? Do I just buy the tallest siphon that will fit in the cistern?
Cheers

 

[swbjackson]

Doesn't matter unless the cistern is a modern one with an internal overflow.

 

[swidders]

Providing it empties the cistern when operated, it matters not.

 

[kirkgas]

if the syphon is too short it will overflow down into the wc before it has allowed enough water into the cistern to flush properly, and if you reset the level to stop it overflowing it wont have enough water in it to flush properly