I strongly second what Patrick said about strings(J.D. Crowe GHS), tailpiece (Kirshner & cranked down)and bridge/s - although you might also consider one of the Emerson Power bridges.

Last fall I got an old Vega Tubaphone, added pretty much those elements, and now play it both for 3-finger and clawhammer. It's still not as loud as my resonator, but boy is it sweet sounding!

One other thing you might consider - Deering makes the John Hartford model with a "pop off" resonator and a bubinga wood tone ring. They're supposed to be pretty hot & great for interchaning the two picking styles. They're not cheap, however.