had a search through the forum but can't find any relevant info, so - what are the best choices of 17" wheels to replace the 18" rear in my GK73A ?
I've looked at GK76A, SV650 and GSX600F wheels - any recommendations or suitable alternatives ?

Ta

Garry.

GK76 + 73sp rear wheels fit and are 4.5". Bandit and later std 73 wheels fit and are 4.0".
You need the correct shock and linkage to run the 17's if you're coming from 18's.
If the bike's gonna see the track, or you want to run 160 rear you need 4.5". Otherwise 4.0 will be fine and easy to find.

what is the correct shock and linkage when fitting a 17" rear wheel ?

If you are going from 18 to 17 you will need to check that the linkages and swingarm etc are all compatible. Otherwise you aill end up with a poor handling bike.
Have a search through the forum(s) - bound to have been done before.