Will you have batteries in the back also? From your numbers you look to be shedding a fair amount of weight from stock. Could you increase the number of batteries to increase the range? Can you maintain a similar weight distribution as stock in order to retain the handling characteristics? In round numbers, what do you think you'll have into the conversion dollar wise?
Pictured is the rear battery box in my parts car. It will hold 14 batteries and weighs about 120 lbs. I decided to construct it out of some quality plywood because it will eventually be upholstered to match the interior and it needed to be completely non-conductive because of the proximity to passengers. The batteries are actually attached to the chassis through 8 steel threaded rods, the plywood box not really structural.
By my estimations, the front batteries and motor and components weigh in around 350lbs. This is pretty close to the weight of the stock engine cooling system etc.
Total electric conversion parts are going to run 10-12k. A more detailed parts list to come...