Richard Holdener dyno the the top hp packages of chev's 302 327 and 350 and all made 350-355 hp in dyno trim. A little off from there ratings but shows 350 hp is a good amount power.
350+hp 318 is a fair easy goal, the 80/90's 5.0l mustang only dynos 265 hp you don't need much hp to have fun.
