No matter what anyone might tell you, don't kid yourself that it's a straightforward or 'bolt on' mod. It's not.
That is unless you've got a lot of cash to throw at it, but I'm guessing that everyone considering this mod and reading this thread is like me and wants to do it as economically as possible but without cutting corners on worn parts.
What you'll need to get hold of and factor in to the cost:
NC35 top and bottom yoke and forks (£200 off ebay)
Shop rebuild of forks (£90 from A.B.E.)
Steering bearing set (£20ish)
Clip-ons (£40ish)
Calipers (I paid £120 for a good set of 2003 cb1300 calipers, same as CBR600F3 I believe)
Master cylinder to match the calipers (£25)
Hoses (Hel hoses were about £60)
Brake pads (EBC pads for the above were around £45)
Mudguard (£30ish)
(Which takes my current total to around £630)
Stuff you can reuse:
Switchgear
Grips and throttle mechanism
Levers
Ignition switch
Front wheel
Brake discs
Axle and spacers
NC29 stem
The hard part
Swapping the NC29 stem into the bottom yoke of the NC35.
This is the point I'm at right now and it's a real ballache. You will either need to do the work yourself or find a machine shop willing to do it for you (no easy task).
Here's some pictures so you know what I'm talking about:
Comparison of NC29 bottom yoke and stem (left) to the NC35 (right). Notice how the 35 is slightly shorter. That's just enough to mean the locknut can't be put on when you thread it through the headstock. Arse.
The stem is WELDED to the yoke on both the NC35 and NC 29 bottom yokes. You will need to remove this on both, press out both stems, then press in the NC29 stem into the NC35 yoke, then reweld it.
NC35 bottom yoke weld.
NC29 bottom yoke weld.
I'm told the 'right' way to remove the weld is to use a lathe.
I'll pass on what someone suggested to me, but do this at your own risk. Carefully use a grinder to take the weld off. They also suggested cutting a slot into the NC29 yoke and basically destroying it, but that would theoretically allow you to push out the stem without the need for a hydraulic press.
To get the NC35 bottom yoke, they suggested that I cut off the stem just above the yoke and carefully grind or file away the welded section, then slip a hacksaw blade through the remaining piece of stem in the yoke and carefully cut through it, all without damaging the yoke. Then drift out the piece you've just cut.
This all sounds pretty extreme to me, so if you go this route and mess it up, you've been warned. I'm only trying to pass on the suggestions made to me in case someone braver reckons it's the way to go.
I was quoted £100 for a bike shop to sort this out for me.
The other way around this is to shell out for a CNC bottom yoke. Tyga don't do a NC29 stem, but at the moment Gavin at Jap4performance is finding out if they can machine one up for me to press into their NC35 yoke set. I'll update this post when he gets back to me.
Then of course you could spend as much as you like getting a custom set of yokes and stem made up.
Hope this is useful to someone. Why anyone would spend £500+ on an NC29 is anybody's guess (unless like me they realise the NC29 is awesome), but I'm still feeling the love for the mod even if it's a pain in the arse at times.
To be continued...
Well said Sir 
