Which model of Land Cruiser are you referring to? Sounds like a 40 series to me. (in which case, you're in the wrong forum).
Rough Country suspensions are generally considered fairly low end, and the "kits" are not generally very complete. If you're trying to go up 4" you will need to address brake hose lengths, caster correction, bump steer, drive shaft angles and perhaps a few other things.
Once you've gone up, you'll want to consider what tire size you want to run, and if it's a bigger size, you may want to address your gearing short-comings.
If you want a better suspension, then you probably should consider doing something a little more custom - like putting in 60 series rear spring all the way around.
Most people do not drill the original spring pins, it's much more economical to purchase ones that are already made up. Aim for a better brand as opposed to a 'cheaper' brand.
And yes, greasable shackles certainly smooth out the operation of the springs and the shackles and make for a smoother ride. Not so much on the fixed end, but very much on the shackle end.
Adding greasable spring pins does make the removal and replacement a lot easier, and if the suspension has been in place for a long time, and the parts are corroded, you're more than likely just going to have to replace these parts with new ones in any case. Parts that have been torched and beaten with a mallet don't tend to re-install very well.
There is sometimes a debate about grease attracting dirt etc. but that's a surface attraction and dirt does not get in to the working parts as the grease is pumped in under pressure and pushes any dirt out that might get in to the where the pin and bushing meet. It's a really a BS argument in my opinion.
I have to keep telling people to build their trucks with a purpose in mind. Don't just do something (ie: spend money) in a manner that is not going to give you best value or suit your purposes in the longer term.
Hope this helps.
~John
