But I definitely will fit big bore kit to NC29 if I have one :)))

you'd be surprised what the 400 frame can cope with.

23 and 29 well over engineered and takes the cbr6 lump with ease.just get the suspension sorted and its sweet all the way.dont knock em till you have tried it,trust me.waza's will nail any 400 every time and plenty of bigger stuff!also remember the 6 lump is possibly lighter than the 4 or very similar due to cam geared(wider) 4 lump.
all the latest stuff is more topend and no midrange balls unlike the 90's engines.

So!!!
We know it wasn't PARUS, so who's bought it then?