Iceberg Slim was born in 1918, grew up to be a pimp in Chicago, and gave up pimping in 1960. Therefore the slang in his autobiographical first novel must be patterned on the slang of the Chicago underworld circa 1940.
A raise must be a portable container large enough to contain $20,000, presumably a satchel or briefcase. I have never heard raise used that way and I am sure the usage is obsolete even in Chicago,
In current American slang, to pop is to hit or to shoot. Hit is very likely the meaning in your example. The fact that he plans to pop "some", i.e. more than one or two, makes this very likely to my mind, as opposed to speculative indecent alternatives.