Morris Minor Owners Club

Here is a similar arrangement to what you have fitted. Note the additional welded on plate as per your conversion.
http://www.morrisminor.org.uk/index.php ... tions.html

They may be able to supply suitable dampers - well worth a call.

If the bottom damper mounting has been welded onto the suspension arms (both thick and thin) a problem will arise when you want to split the arms to do maintenance on the suspension.