Dave. As an alternative to the original springs you may like to consider a set of Suplex asymmetrical 4 leaf springs. The 4 leaf springs are more supple than the original 5 leaf springs and the asymmetrical design is a relatively new design, from Dan White of Suplex, that reduces axle tramp.
If you wish to contact Dan,an enthusiastic Morgan owner, send me PM and I will send you his contact details.