with this combo I would be cautious about over gearing and too loose of a converter. on an engine dyno this engine may show close to 550hp. i'd try to sneak up on the total timing some; maybe try 36-37 degrees. you can get 2 1/2" mufflers that will flow better than some 3". I wouldn't get lost in the peak horsepower/rpm thing. whatever gains you might be making above 5200rpm may be ate up driving the trans/axle. chassis dyno thing is a different world than the more common engine dyno numbers. in my opinion, chassis dyno is real world and engine dyno can be more pie in the sky.