+1 for genuine bushings. Those poly bushing kits are for the birds. The first thing that sucks is that they limit suspension flex. The second thing that sucks is that they'll delaminate real quick if sand or a small rock gets wedged into them and split right in two!
The Bilsteins are great shocks - I just don't think the 5150's are worth the hassle of converting the mount style, nor does the valving ever seem to work out as well as OME. Likely the ones you have are valved very stiff, and you're about to couple them with a soft spring. It ain't going to ride as nice as it could. I ran 7100's in my RRC and they worked well off-road, but they sucked on the highway. My buddies with OME kits seemed to have the best of both worlds and spent a lot less money that I did.
OME is a great choice, but if you put on those 2" lift springs you're going to also want bigger tires. After having 2 jeeps, the rover's 3.54 gearing on 32" tall tires really bugs me. Most people just live with it.
Given your intended use for the truck, Bilstein does also make a great set of replacement shocks that are 100% bolt-in:
http://www.roverparts.com/Parts/9279D.cfm
There's also a matching steering dampener from AB. These are firmer than stock but aren't harsh. Handling is much improved over the woodheads. I've been in an LWB rangie and a D1 that's run these and both were great riding trucks. They're just not very popular because, essentially, it's still stock.
If you're worried about load, you can get a pair of slightly stiffer factory springs for not much money. Nobody ever does this really because the OME kits work so well, are cost effective, and a bolt-on medium duty kit will clear your choice of tire under 33". If you do want to investigate getting replacement springs with 0~1" lift, check out the P/N's here:
http://www.members.shaw.ca/jbarge/springinfo.html
In my opinion, for an adventure type truck like you're talking about that's going to see plenty of highway - a fresh pair of genuine springs for the rear and a set of these "baby" Bilsteins would work great and won't encourage you to put on bigger tires, keeping the fuel mileage close to stock. Plenty of people will disagree with me ... edit: but they probably don't have a built jeep keeping their rover company in the driveway
cheers
-ike