Ok, so you have a new 4.8grx and it has the stock nissan patrol suspension in and you want to lift it about 50mm and keep the ride soft.
I have the same GRX and I had a lot of shocks/coils etc and you will find it hard to get a 50mm lift and still keep it as comfortable as stock.
I have heard from a few people that trim packers or spacers are not good as it will make your axle articulation decrees by the thickness of the packer but I am not sure on this as I have never tried it.(think this is more related to independant suspension setups)
You would also need to get new shocks to travel the extra length of the packer and most of the 4x4 shocks only have about a 20mm extra travel length over the standard shock.
There is a very nice shock test article somewhere on this forum that actually tells you the shock lengths, firmness etc which you could use to give you an idea when getting a new shock for the spacers if you go that route. (pm me your email and i will email it to you as I can't upload it as it's about 4mb)
I just got an OME suspension coils and shocks and it was suppose to be only a 20mm front lift (2972) and 30mm medium back (2982) lift but in reality it was more than this and it changed my caster my 1.5 degrees. still rides nice thought. I matched it up to the N19 front and N29 rear all yellow nitro charger shocks, I don't like the new Nitro charger sport as they are a bit too stiff. I wanted the N19 c shocks but they are discontinued which is a pity as the C stands for comfort so they are nice and comfy.
Interesting that OME do not recommend trim packers in the rear suspension, they only use it in the front suspension for leveling the patrol out if required.
You will have problems with your rear stabilizer bar if you put 50mm spacers in and you would need to get extension brackets, OME makes a kit part number FK18, only about R350. It's good for a 2 inch lift so will be adequate.