Rust in tight places

I'm removing surface rust on a 4130 fuselage prior to priming.

Assume I'm in a place where I can't use my sandblaster.
I need to get into the tight places of a cluster to remove surface
rust.
I can get pretty deep in the cluster with emery cloth, but there is
the last 1/8".

There are rust converter chemicals on the market. Is it OK for me to
use
a rust converter prior to priming or am I fooling myself? - Mike