Having fitted quite a few of my wiper blades to different cars no two Morgans are the same as we know .
What has surprised me the most is the variation in the way the arms have been bent by the factory ,later cars seem far worse than older cars .
The wipers should sit parallel with bottom of the windscreen and not over lap on to the fame.I am amazed at the poor and cockeyed fit that some newer cars have ,all down to poorly bent and fitted arms by the factory.

So I would suggest sorting the arms out first and getting the wipers to sit correctly on the screen .
I fitted a set of 7” wiper blades to a 94 plus 8 that still had its original 6” the other day ,.they worked well after removing about an 1/8 of an inch from the rubber at the top end To stop it hitting the top of the screen frame .
Then a plus 4 from 2007 all good except one arm longer than the others ,so again a small amount removed from the top end of the rubber to get it to clear the top of the windscreen frame .
I have a good supply of blades so thanks to all who have ordered and keep the requests coming .
One question asked was regarding replacement rubbers .As the blades are of a standard type the refills can be purchased from most car stores or on line and cut down to the required size ,just save and reuse the two original stainless steel strips.