It still has a lot of termite food so frame flex with a higher torque engine could be a problem.A 400hp small block will have a radical cam, high compression, and get 12mpg on a good day. You can get a bone stock LS/LT with 400hp that idles baby butt smooth and gets 20 plus mpg if any of this means anything. Your wife can drive it to the store and let it idle with the a-c going.
