sure forged will be stronger, but where is he getting his pistons that cost $900? I'd expect to pay in the $600 ball park for a set of forged pistons.

but for what you want, cast will be fine. my 5.9L has stock cast pistons in it, a cam, intake, headers. it's putting 285hp 325 tq to the wheels and running 14.3 with abysmal 60' times on street tires (indicating it has the power to run 13s if I can get it off the line) in my 4000 lb pick-up truck.

If cast pistons work in that application, why wouldn't they work in your 4200 lb vehicle?

as mentioned, you just need to be sure your tune is in the ball park and keep it from detonating. but even if you had forged pistons, detonation will still wreak havoc on your motor and tear up rod bearings/main bearings, and forged pistons won't protect the bearings.