I'm going to pick up a 89 quest on Sunday. Owner says he hooked the battery up backwards and says it now cranks and barely idles but won't rev past 3000k what all should I take

Anyone with a Starquest that has pulled their dash has been... dissatisfied with this http://i492.photobucket.com/albums/rr285/manlavi90/IMAG2473_zpsf559b6e8.jpg once they pulled the dash off.   I've come here today to ask some questions. I want to get rid of a lot of things on this harness, for example, the belt control box. How would I go about removing it and all associated wires? Or is that not possible because it is in some way wired in with ETACS?

Like title says. New in box. Cost from dealer is 380. Which of course is showing NLA now.   http://i1086.photobucket.com/albums/j442/creakyjoints/PARTS%20FOR%20SALE/20150128_115335_zpse0c96fad.jpg   http://i1086.photobucket.com/albums/j442/creakyjoints/PARTS%20FOR%20SALE/20150128_115326_zps9894eab1.jpg   Looking for 300 obo.

Hope you see this Ken, have a great day