The rebound spring doesn't affect the ride height.
Unfortunately in some Morgans the rebound spring is under compression which is not good as, contradictory as it may seem, it adds to the stiffness of the main spring resulting in extremely stiff front suspension. As GoMog has suggested, a simple improvement can be effected by shortening the rebound spring so that it is not compressed under static conditions.
I'm going to look into this on my recently acquired Plus 8 as a first step.
There will be numerous opinions on improving the rear suspension and I'd be surprised if a consensus will be found on this forum ! Generally speaking, using leaf springs as a suspension medium and as the ONLY means to locate a live axle is not good practice, unless for modest power outputs.
I envy MGB owners, they have numerous upgrades available to them. From fibreglass or parabolic springs to every location device under the sun all available off the shelf from the MG club or various independent specialists.
I'd recommend the book " How to Improve your MGB, MGC and MGB V8" by Roger Williams, it has so much useful and informative information that could also be applied to Morgans, particularly the V8.
