I'm with Astro, go with the 455, some frame ties and maybe even a 4 or 6 point cage. Might as well, the back seat is pretty much unusable in the F-bodies anyhow..... Depending on how much $$$$ you want to spend and how much power you want, Edelbrock makes a very nice set of aluminum heads for the poncho's. These heads along with the matching intake and cam with a good free flowing exhaust would make for a strong running torque monster.