GURPS players never seem to do things by half measures. So it shouldn’t be surprising that one of the most thorough ametuer Victorian RPG sites would be for GURPS (Third Edition in this case).
The Victorian GURPS, or “GURPS by Gaslight” page, by the Whitley Brothers (Mark & Jared), has a remarkable depth to it…
About a Dozen Characters
Five Adventure Seeds
Notes on Seven Full Adventures
The best is the almost encyclopedic Victorian Roleplaying Themes: 18 expansive “themes’ (from High Society through Time Travel) that provide solid lists of “Historical People and Events”, relevant “Books, etc>” and appropriate “Overtones”. There’s even notes on Using and Mixing the Themes.