howdy long time no speak, i have been wondering and as u are what can only be classed as a god in things to do with fzr's i am planning on putting 1 of our fzr's on the road for myself aslong as the op's go ok on my knee, is it poss. to bolt on 600 cyclinders and head on to the 400 base???

Um ... probably.
I think you end up with a 560cc engine as the stroke is a bit different - the conversion is on FZR Archives