If you set the blades in the vertical position (I turn off the ignition in mid stroke) you can then remove the wiper arms and use a pair of pliers or something to grip the wiper arm to twist it slightly one way or the other.
I have done that and it helps a lot. The standard blades are not very good and I have made a set using Bosch blades for the doner bits. Someone on here suggested it a while back. I have also found that the stroke of the blades is about 5° more than it should be. It is one of those things that considering the number of units used by Morgan every year should not be impossible to order the correctly geared wiper motors.