Not sure you'd want to do that. The drivetrain is pretty stout; rear axleshafts make GM 1/2 ton stuff appear tiny, and the front coarse-spline birfields in a '72 aren't nearly as bad as they're made out to be. The motor won't make much power or rpm, but has nice torque down low, and with that huge flywheel, it'll keep running at very low rpm. Gearing becomes an issue, even with 33s, so lots of people like to swap an SM420. Steering and brakes will let you know you're driving a vehicle that's 34 years old - ours feels much safer with disk brakes instead of the 4-wheel drums.