10 sec. 318?

The bottom end is where the 318 shines. If you're looking for 400hp, read the junkyard Jewl article. If you are handy with a dremel and some other tools, it is a DIRT cheap route to 400hp from a 318. The 318 block is EXTREMELY strong. It was designed strictly as a workhorse. At the time the 318 was designed, the 340 was the powerhouse small block, the 318 was designed to be indestructable. A stock 67-74 short block is gonna have a forged crank and flat top pistons. As you'll find out in the article, the only draw backs with the 318 (other than lack of cubes and a bore that is slightly less than optimal 4" ) are low compression, head flow and factory cam specs. Ported 302 casting swirl port heads solve the compression and flow issues in one shot. As shown in the article, adding the right cam, intake and exhaust resulted in 406HP. The hotrod magazine guys claim to only have spent $1400 (although they tend to get crazy good deals some times) I personally bought a pair of these heads already setup as per the article from a machine shop in MO. for $600! Anyways, there are some REALLY good 318 setups that cost A LOT less than $6000 if you're looking for the 400-500hp range.
Here is a link to the now famous article.

http://www.hotrod.com/howto/113_0304_318_small_block_build/index.html

and here's a link for the 390 stroker kits. This one's kinda expensive and I've found 'em cheaper, but this gives you an idea. oh yeah, I checked and they make a forged 4" crank too

http://www.campbellenterprises.com/318-stroker-kit-mopar-318-5.2-stroker-kits.php