Tom, personally I think your asking price is a bargin for someone looking for a 71 Mach 1 with a 4 speed which I was years ago, finally ended up settling for a 71 Mach 1 with the C6, couldn't find one with the 4 speed that wasn't either way out of my price range or a rust bucket, I searched for a long time before giving up. Sounds like a great project car and worth investing the time and money into restoring it. After spending so much time and money on mine, I now realize how import it to spend the extra time and money up front and get the best project car you can to start out with. My only regret is not holding off until I found one like you describe with the 4 speed.
Thanks, That is exactly the way I looked at it! Spend more money up front for better results later. This has been a hard decision for me but I have two little kids (1 and 5) and a job that is very demanding and i realize as my children are getting bigger I have less and less time to even think about the car.