Try EZ electric power assisted steering (EPAS) Link Below.
EZ EPAS

They have a dealer in the USA called American Powertrain. Cookeville Tennessee. Link Below
American Powertrain

EZ have done quite a few Morgans in their time and should be able to advise their US Dealer on the way forward.

I fitted their system to my 2009 Roadster and have been very pleased.

Bob

2009 Black Roadster
1999 4/4 2 litre Zetec