The early cars had Suplex shocks but these were soon changed for Spax. Later there was a Suplex upgrade option but there were issues with these so I don't think they were very popular.
I'm not sure if yours can be refurbished but in any case if you can consider upgrading as it does make a difference to the ride and handling. In order of price/performance I would suggest you look at the shocks listed in the Alternative Parts List:
Spax Standard or upgraded Adjustable M3W shocks only available from Morgan dealers.
ATR Shock Absorbers. ATR MOG 001 Front. ATR MOG 002 Rear. Available from : www,dampertech.co.uk sales@dampertech.co.uk
Ohlins available via M3WServices, Krazy Horse and BG Motorsport.
I would heartily recommend the Ohlins which give a much more compliant ride and improved handling through better wheel control.