I have a larger cam and different heads my 5.7 puts out about 310 HP. anything larger and the overlap in the cam would not work well with the wet exhaust..... 5100 RPM trimmed just right.
I've added about 300.00 lbs of additional permanent, stationary equipment (mostly stereo stuff and batteries) and still can get her to 55 MPH with no issue, the launch is NOT great unless there are a few in the front.. may be looking at trim tabs or something in the future.
My cousin races sprint cars and has a few led valve cover castings (they fill valve covers full of lead and bolt the casting onto the cars for weight... I may place a few in the bow just to see what happens sometime
EDIT - Also much over 300 HP and your just asking to grenade the alpha drive.