Andy, I have no idea about cost but I would be prepared for a big bill plus around £1k labour I reckon.
There is definite handling improvement, steering being very positive, but will it be worth the cost? That will depend on how you use the car, if track days and fun runs are your bag then maybe. To get the benefit on roads with say a nice set of bends your probably going to be pushing a bit too hard, from a sensible driving perspective.
One thing to remember which a friend pointed out to me, is that there is still another issue with the rear axle, under cornering the wheel on the outside of turn will tuck under at road contact. This is due to drive shaft flex, it bends, the fulcrum point being the outer drive shaft bearing. I believe there are a few videos about showing this happen. There is no simple solution for this other than to replace the drive shafts with beefed up ones, but in my mind that might put undue stress at the bearing point on the wheel, or independent rear suspension with floating half shafts.
In my mind a Morgan corners and handles quite well already if it has decent adjustable shock absorbers, front brake reaction bars, and a panhard rod, and a anti-tramp bar for a car with more power, obviously it needs to be setup right as well.
It depends what you want, there will be gains but wether the cost is worth it will be down to each individual's view.
