Every shock is different mate, as is every spring.

One "2 inch" shock might be a lot longer than another, some might have a lot more travel for the same conpressed length etc

Same goes for springs, one 2" spring might be 100mm taller in free height than another.

Manufacturers often package there things together to work well, I.E and 2" spring and shock package from OME would have the perfect lengths to work well together.

The position of a shock piston throughout it's travel will not effect it's dampening, unless of course it's a race style shock with bypass tubes. The harshness your experiencing is most probably related to changes in caster and arm geometry as as result of the lift.

Amada's are a great budget shock, as are the Profender adjustables, both sold by superior engineering. The Amada's are a little stiffer, but they both great, personal preference really.

 

I'm in the same predicament, except I haven't got the spacers in yet,
I agree with jamie4800 in that some kits are designed for the spring set up (soft /hard).
I would suggest looking for a soft to medium shock to suit your standard
The best advice I can give is, talk to a custom suspension specialist face to face with sone measurements in hand,
Compressed length of oem shock, full open length of oem shock, your current coil spacers, age of your oem coils, any extras on the vehicle, bull bar rear bars, any extra constant weight, do you tow, how much how often?

You would only need big bore shocks if you carry /tow heavy loads or do lots of heavy flex tracks.
Basic off road with more beach then country would call for a softer ride.
My 2c

 

As a rough guide to shocky lengths see if you can download the ARB Old Man Emu shock sizes.
Their 2" shocks seem to have really good lengths compressed and fully extended to result in quite respectible travel and comfort. I will see if I can dig out the sizes for you.

Anyway it is hard to find other 2" lift shocks with better travel. Sure you can get longer shocks but most will result in you loosing some of the compressed length upward travel.


EDIT:
ARB OME Nitrocharger 2"
front mm
N19 closed 320 open 495

They also do a Long front shock in the Nitrocharger Sport series:
60013L closed 322 open 555

Rear
N29 closed 396
open 656

 

Ok still getting this sorted,
I've purchased some castor bushes to see if this reduces the harshness of ride.
I have also considered drop boxes, however I'm not sure these are necasarry.
With 285/65 17r km2's and 2 inch spacers, this is already enough lift and bordering to much lift for what I'm after. Once steel bar, winch, second battery and the engel in the back I think it will sit about where I want it. After this, I'm not even sure I will need castor bushes.

Found these on eBay. They seem to good to be true.
FOX Shocks Nissan Patrol GQ Remote Canister Direct FIT Comp Truck | eBay

 

Sounds like you should be running 30mm spaces with 2in shocks, there is no need to run racing shock unless you are racing, don't waste your money mate! if you would like a softer ride get some comfort springs and adjustable shocks like rancho or tough dog. hope that helps