A word about MGB conversions........
The first thing ..... is that new MGB springs are now such poor quality, that they have a very limited life before sagging, and I imagine that this is in part due to inferior quality steel. In the good old days, leaf springs went on forever, except on my Midget which ate them due to my harsh treatment.
Coil over dampers need to be close to vertical to work effectively, and the shorter they are, the more important this is. There has been one case I know of with an IRS rear end on a B, where the damper shaft snapped due to stresses induced by the angle. The IRS kit uses a Sierra 4x4 diff mounted in a tubular steel subframe which uses the existing mounting points. It's a good if expensive (£X,000) upgrade, but I doubt there's the space on a Morgan, and you would have to alter the front suspension to derive any real benefit.
The coilover solution using the existing axle is available for the B, you need trailing arms from the front chassis mountings to the axle, and more importantly some form of lateral location. Often this is by Panhard Rod, which doesn't take up much room. My Gilbern Invader had this set up with an MGC axle and adjustable coil overs. Same on the front with a modified TR set up. But the ride was worse than my BGTV8 which I had at the same time. An alternative is an 'A' bracket to the diff, which on the Mog, as Cereal said would need the U tube strengthening. My Dolomite had a similar set up, but Dolomites used to eat rear shockers due to the conflicting geometry. A pig of a job to change as well.
So - It would be possible to fabricate a coil over fix with Panhard Rod, but for the road I really don't think you'd find much difference, and for me, the antique suspension is part of the package.
