On your deal I wouldn't look at any power adders with a good sonic tested 400 block
Put a set of aluminum main caps and ARP main studs along with a good set of M.W heads and a good single plane intake with a 850 CFM or larger carb. with a 4.25 stroke crankshaft with a set of good forged pistons and rods that will give you between 10.0 up to 10.75 to 1 compression ratio for todays pump swill and tune it up so it EATS
Have fun, enjoy the thrill of lack of traction