You can't convert the weaponry from the Hunter to the Police Maverick, as far as I know.
You can try and replace the DFF and TXD files of the Hunter with the DFF and TXD of the Police Maverick, the Hunter is replaced with the Police Maverick then.
Then open carcols.dat and replace this line...
hunter, 43,0
...with this...
hunter, 0,1
...that way the Police Maverick won't be red when it appears in the game
Just a suggestion though.