340 max camshaft with exhaust manifolds
^^^ this.
intended purpose and driving style are nearly as big of factors as compression, heads and induction. stop light eliminator? hot street ripper? something with a bit of manners?
since you mentioned "sleeper" i'm guessing you want something that passes the eye test as resembling a stock dressed motor, ie not a big *** tarantula intake topped with a 1050
that said, what do you got and what are you working with?