Select the gzipped text section (or provide a range, e.g. :/^$\n\zs/,$
). Then you can unzip the part by piping it through the external gunzip
command (which naturally must be installed and accessible):
:!gunzip -
When I tested this, the buffer had to be opened in 'binary'
mode: :edit ++bin filename
. Also, I got gzip: stdin: unexpected end of file
after the unpacked contents, but that probably can be tolerated.