As said, permutations on the springs are endless; and then there is how the chassis was converted to coils, and the possibility it was done badly, or the person who converted it had the notion to weld the spring mounts on slightly lower to add a bit of extra 'lift'!
But, if it used Disco springs, and had mounts welded on the chassis at roughly the right height; the Disco has a heavier body, and engine, so I'd expect it not to ride quite so low to begin with, and possible that the weight distribution on the springs is different too; I presume we are talking about the tidy blue SWB in your profile; which is shorter than a disco too. Being shorter, weight on the back has less leverage to compress rear springs, and I thought the disco was supposed to be a bit tail heavy, so would have thought that disco springs would have made it sit back-end high, not low; but?!?
Could be that the Disco's tail heavy, but Series doesn't have so much gubbins under the bonnet, so might be that theres not the same weight on the nose!
either way, problem is to get the angle more suitable, and try and make it a bit more stable!
I would NEVER use spring clamps!
Horrendouse devices, prone to popping off when you least want them too!
And you could spend forever swapping and changing springs of different rates and lengths to get the angle you are happiest with.
And you DONT really know what you are starting with? Is it s astock Disco spring, or an HD one; standard length or over-length, or what.
You obviousely want to take some length out to reduce the roll centre, and you want to take a little more out from the front springs than the rears........
But as a starting point, might be worth swapping the fronts for the rears, and seeing how that sits; before TENTATIVELY taking it for a test ride (Somewhere deserted..... slowly!)
Beyond that; go to a pro; used to be a couple of people that advertised 'custom' springs, think British might do it; tell them the corner weights of your truck, or the axle weights, and the length the spring needs to be compressed to give the ride height you want, and they can usually do some sums, and tell you if they have any standard springs that are close, or if not, they will 'cut down' a standard spring, retempering the top coils to give the square end, to suit. They aren't THAT expensive; more than a set of coil-clamps; but a HECK of a lot safer!
As a note; local tips often have a weigh-bridge to find your axle weights; Have a word with the operator, during a quite period; they'll often weigh either end for you for a small donation to the beer fund! - we used to use bath-room scales for comp-cars, but think a LR might be a TAD heavy!
