From looking at the Rugers, I think that you'd have a problem with topstrap thickness if you moved a rear sight much further forward.
I'd say you have three choices:
1) Go with Vaquero and install the tritium vials in the factory fixed sights.
2) Install S&W tritium sights on a Vaquero frame. The cost would be $100 for the sights themselves and at least $218 for the machining required on the Vaquero frame. There would be extra cost for adapting the front sight insert.
3) See whether the Meprolight tritium sights for the GP100/Super Redhawk with fit the Super Blackhawk. The cost would be $140 for the sight set, but you'd still have to find a way to adapt the front sight.
Jim Stroh at Alpha Precision might be willing to work with you.