how much £\'s
 

how much would/could i expect to pay for a big bore kit? for 600 SS (96)- been searchin all the threads but cant find any info on prices

Nelly is your man!

If your not racing it it would probably work out cheaper to source a 750SS motor and Exhaust and then sell your £600 engine on.
The person that Senna3 got his spare 600 engijne from did just this to his 600 Monster which is now a 750 Monster.