Id buy a 2013 Shelby, go for the 650 HP. Will be pricey though since they are 65k. Or wait until all the current Shelby owners dump there 11-12s and get one a lot cheaper than sticker.
I know you like to pay cash, so frankly if your going to get something classic you should have kept the GT350!

I also don't think Id get a Boss unless it was the Laguna Seca, but I don't know nothing.