Yes sure it will work in your Mehran 2012 VX and it will perform better as you will be driving on Petrol only. Get is installed from Suzuki 3S dealer, it will be 1-2 thousand more expensive than open market but they will do the good work.
If possible then go for SANDEN A/C, as its cheaper than DENSO & put lesser load on Engine and provides good cooling. Since everything will be new so your A/C will work pretty good and you can use Window Shades to block direct sun-light hence better cooling.
I'm not sure about current cost, but you can call couple of reputed A/C shops in your area, get quote form them. And then call difference 3S Suzuki Dealers and ask for their prices. Make your mind and get it installed