That is why I said stock displacement 318. Once a motor is bored out it is no longer "stock displacement". Yes you can fairly easily get 400 hp from a bored motor with bolt ons such as magnum heads and full roller valve train. I didnt say it couldnt be done, I said "you would be hard pressed" from a "stock displacement" motor. Those bolt-ons can get pricey to.

 

You can get a 318 to 350hp if you have a shop do some stuff. It will cost about $2500-$3000. And you can get it too around 400hp with some more stuff like a shift kit, high power oil pump, cam.

Here is a good way to go.

Get a set of KB167 pistons. Have the block bored to the piston specs,
deck
the block to a height of 9.588". that will give you a zero deck.

Recon your rods with ARP bolts.

Balance the assembly.

Have your stock heads redone with 1.88/1.60 valves. Have them ported. A
good
bowl port and take as much out of the pushrod pinch on the intake ports
as
you can. There is a lot of meat there and it can really be opened up.
Have
the spring pockets machined for Comp 995 springs.

A great cam for what you want would be a Comp 20-670-4. I would get the
whole kit, your going to need it all anyway. K20-670-4. The kit comes
with
cam, lifters, timing set, matched springs locks and retainers, seals
and
assembly lube. You will also need new pushrods. That 318 is a roller
engine
and you will not be able to reuse the pushrods. 7820-16 if you use
stock
rockers and 7821-16 with adjustable rockers.

Top it of with a RPM intake, air gap or not. And any good 600/650cfm
carb.

This will get you at least 350HP and nice power curves.