It depends on your usage and also the weight of the vehicle. On my 90 I've got the terrafirma springs (medium duty +2 inch) and their +5inch shocks, the 90 handles really well and still flexes up pretty nicely
The only problem is that the back is a bit too firm, At the moment I have no roof and just a rollbar and a highlift jack in the back...may change for the light dutys. On the plus side, the 90 tows like a dream though.
As said before, some people get away without castor correction and others have to do it, mates of mine have had both experiences.
Your budget of £800 sounds plenty, but think of every little thing you
may need?
- springs
- shocks
- front turrets/rear shock mounts
- extended brake hoses
- wide angle/double carden props front/rear
- castor corrected radius/trailing arms
- spring seats
- retaining rings/bars
- dislocation cones
- new bolt set
- new bushes
Also consider the downsides e.g.
cost/time/effort
possible poor handling
knock on effects of other components: prop ujs, transfer box output shaft bearings...
also access to your garage/workshop/car parks etc
After the lift and new tyres, I had a problem with getting my towbar low enough to tow twin axle trailers also