Yes, the Nemesis was a notable vessel and one of six gunboats ordered by the 'Secret Committee' of HMEIC during that time period. She was the largest and all differed in details.
Nemesis, along with Phlegethon, Ariadne and Medusa were all built by John Laird at the family's Birkenhead Iron Works. He was a pioneer in iron ship construction using bolted, overlapping joints as used in boiler construction. The other two gunboats, Pluto and Proserpine, were built by Thomas Joseph Ditchburn and Charles John Mare in London.
A builder's model of Nemesis was exhibited at the Chicago World's Fair of 1893 and may still exist. For actual plans I would suggest the National Maritime Museum first. If no luck there I would contact the Wirral Archives in Birkenhead as they retain the vast majority of Laird's records. The staff is professional and quite helpful.
The third suggestion is the UK national archives for a copy of Nemesis's tonnage admeasurements from 1857-59. A set of lines can be derived from them. She was registered as late as 1859 in Liverpool.
Finally, the Williamson Art Gallery in Birkenhead has a large collection of Laird built builder's models on display. The Nemesis may be there or at the Wirral Archives. And as you know a number of illustrations and lithographs exist of her.
Between all of those sources I think you will find something of use.
All the best,
Bil
'Too many ships, not enough time'
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