Here's my take on it, having had several aftermarket shocks on my Fazer, together with K-tech modded Fazer forks and then K-tech modded R1 forks.
The stock shock is undersprung, poorly damped and usually dies after about 10k miles. It can be refreshed and resprung, and revalved if that's what you want but the cost works out more than fitting an R6 shock with appropriate dogbones.
The R6 shock is much better quality than the Fazer OEM item but not quite as good as a quality aftermarket shock. I've had Hyperpro and Ohlins on mine over the years but I now have the R6 version and frankly there's barely any discernible difference for fast road use. Certainly not the way I ride these days.
Rider weight 70kgs not including kit.
The stock forks are fitted with dual rate springs which are too soft in the first part of their stroke and too stiff in the latter. In addition, the hi-speed compression damping (non-adjustable, determined by the crude design of the valves) makes for a jarring ride which can't be fully dialled out with the damping adjuster, since they only alter low-speed damping response. The rebound damping is too little which means that using thinner fork oil to improve the ride quality can lead to too little rebound damping, even with the adjusters on max.
I've tried OEM forks fitted with Hyperpro progressive springs and they are a worthwhile improvement over stock for a reasonable outlay. Fully modded OEM forks (K-tech, Maxton, take your pick and pay your money) are a bigger step forward and the revalving resolves the issues mentioned above.
R1 fork conversions usually alter the steering geometry (depends on what you do with the yokes and fork lengths), making the bike steeper and quicker to turn. My R1 forks have K-tech internals which make for a quality ride in addition to the quicker steering response. For heavier riders, the loss of a little ground clearance might be an issue but for me it's not been a problem.
So, what to recommend to the OP? The R6 shock is as good as you need, IMHO. I suggest you consider fitting linear rate springs appropriate to your weight (speak to K-tech, Maxton etc for advice) along with whatever fork oil and air gap they suggest. Drop the forks through the yokes 10mm and see how it goes from there. If you plan on keeping the Fazer, consider spending more on a complete fork revalve. It will be worth it in the long run and will be as good for you as dropping time and money into an R1 front end with unmodded R1 forks.
Just my five pennyworth, of course.
