Need gears (4.11's with LSD) and a 3000 stall converter
Better heads (after market, 64cc chambers, 160 to 180cc intake ports). 170cc Edelbrock Performer heads (not rpm) would be a good choice.
High compression with aluminum heads (10.0 to 10.5 cr)
Roller cam would help a lot to make more torque (225 to 230 degrees duration at 0.050, 108 to 110 LSA)
Edelbrock Performer RPM intake (not air gap) and a Holley 750cfm 3310.
Full length headers (1-5/8 tubes with 2-1/2 collectors)
You can make 400 ftlbs of torque and 400hp with a 327 but it will be in the upper rpms which requires a lot of gear and a loose converter.