yup that is the way to do the frame rails on your car first time i seen that done was by frank B of bay city on a blown sbc maverick about 28 years ago . are you going to rework the floor pan for the EX ? i have two blocks to build a 496/512 have a nice set of alum canfield 320 rec heads and some other stuff just laying around could wip something up EZ if you like solid roller cams ?