Magnum research makes a revolver in 45-70 with a 7 1/2" barrel. It is single action in stainless steel and I've seen them as cheap as $900.

More pistol than I care for. The 500 S&W revolver can be had with a 7" barrel, and wouldn't be much less than the 45-70.
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The ultimate result of shielding men from the effects of folly is to fill the world with fools.
-- Herbert Spencer, English Philosopher (1820-1903)