Vim search and replace: moving [5:0] position in a line

I have code lines like these:

assign o_BVALID_COMP = 'h0;

assign [79:0] ARUSER_COMP = 'h0;

and similar variations with single bit and bus assign signals...I want to change this to following in my vim file:

assign o_BVALID_COMP = 'h0;

assign ARUSER_COMP [79:0] = 'h0;

How can I do that??