It is not hard to make over 400 HP with most of the parts you listed, the camshaft, headers and carb size can have a large affect on the HP and torque made by the motor.
The first motor I built for a customer that wanted it dyno tested and tuned made right at 500 HP, it was a 9.5 to 1 compression ratio pump gas 1962 Max Wedge motor that made 499.3 HP at 5900 RPM. It was bored to 4.250 and had a decent solid lifter camshaft with the stock dual AFB on the stock crossram intake.
The next one I dyno tested and tune for myself made 430 HP at 5500 RPM, it was a .030 440 block with TRW six pack pistons and a stock 1970 cast iron six pack intake with a set of stock vacuum six pack carbs and a mild hydraulic lifter Comp Cams camshaft.
The last pump gas stroker pump gas motor I made for myself made 612 HP at 5500 RPM and 544 Ft. Lbs. at 4500, it was a 400 block bored to 4.375 with a 4.25 stroke crank, ported big valve 906 heads and a Com Cams custom ground solid roller lifter cam and a low deck Eddy six pack intake with a set of slightly modified 1970 six pack carbs, that motor exceeded my expectations and was a real hoot to drive
What brand and type cam are you running and what size headers and exhaust system?