i would stay away from the larger tb, until the motor is worked over. same for the intake manifold, unless ou want to go the lt4 route. id do some long tubes, cam, rockers and tuning. if the car has an auto you will see a nice gain buy going to a stall conveter.

and i would also look into some suspension upgrades, since there is no use in making power if you cant use it. sfc's are a must for fbodies, and lca's just about eliminate any wheel hop.

and of course just make sure the car is in good running condition...fluids, belts, hoses, tires...the usual