This would actually be a good mod. You will need the 749r rocker and the 749r tie rod. Compared to the price of the shock these are not that expensive.
You dont need to change the swing arm!..............Technically the geometry is the same, but it sure looks a million time better!!!
As far as putting it on a bp......if you ride 2 up often then its probably not a good idea. If you want to improve your bp for mono riding then go for it!
All the welded swingarms are the same, there's no difference between R and base or Bip and as Andy says swap linkage and tie bar and it should fit on. One small downside is that the 749R also used a different head angle adjustor and fork offset to balance out the more linear rear set-up which was put in there to cope with bumps at high lean angles ( it makes it easier for the shock to move when already mid stroke). I'd think the shaft position will sit lower in the stoke more of the time because of the linear action so its maybe why it also got different offset adjustments to balance this for the track. The 749R is the only bike with that extra eccentric , 999R's didn't have it.
The benefits of this on the road are the way the suspension reacts more easily to small bumps the downside is that hit big potholes or big bumps ( not many of them on tracks) and you'll blow through the travel very quickly which was why the rising rate is used on road bikes. Depends what you are using the bike for I guess.