trying to pull ponnies with little cash

400hp from a 318 is cake and would not be Nasty at all. If you want to throw on a set of Eddy aluminum heads, put a GOOD flat top piston in and a cam with around 230* duration @.050" and .500" lift, theres your 400hp.

Would a 340 with 400hp be nasty and cost a bunch? Not really. 318 and 340 are not that much different