Kz1100 spectre rear shock help

Hi , looking for some advice on replacing the very tired shocks on the back of my 1983 kz1100 spectre , I’ve recently put back on the road after 7/8 years of standing .My main concern is what size of shock will fit , the eye to eye distance is 325 mm , the nearest I can find is 320 mm or 340mm, would I be able to fit the longer shocks without causing problems ? I don’t really want the bike to sit any lower  than already is, I’ve never owned a shaft drive bike before so a bit clueless and don’t want to mess the bike up , any advice would be appreciated , thanks Steve .

Have you looked at these?

www.ikonsuspensionusa.com/?year_id=1561&...ction=vpf-ymm-search

These used to be known as Koni, a well respected shock back in the day.

Both iKon and Hagon have a good reputation.

www.ikonsuspension.com/product/7610-1429/

www.z1enterprises.com/hagon-rs-shocks-st...z1-kz1000-kz750.html

I've got longer shocks from a 900 on my 750 shaft, works fine and I appreciate the higher seat. I think eye to eye is something like 340/350mm. 

Thanks , I think I’d like to raise it up a touch , I was just worried I was going to through something out of sync , maybe I’ve been overthinking it , going to have a shop about and see what a can afford to go with .