I don't see any similarity at all to be honest. Mid 19th century steam vessels are a complete blind-spot in model manufacturers catalogues, so I doubt there is anything you could convert easily. The closest (would be the airfix 1/180 S.S. Great Western. and it is still a long way off- not least 50 foot length yet along a hull form that even though only 15 years older is from another era!)
It is a fascinating period of merchant shipping history but there aren;t even many publications on the subject either!
Looking at this rather nice model here http://www.arago.si.edu/index.asp?con=2&cmd=1&id=76707 , I think you would need to get hold of the plans (if they survive) and scratchbuild.
good luck,
Will