I just picked up an 04 ex on Wednesday. I'd say if your willing to spend that much, scope southern dealers and CL for a no rust having truck. Rust is not worth messing with imo. Be patient, yet diligent since nice ones come up often, but sometimes sell real quick. Plus private party sales are nice cause they're often cheaper and no dealer fee nonsense. 05's are nice with the coils up front, but this 04 is pretty sweet too. My 02 350 is a similar setup to yours, but boy this 6.0 is nice even without tuning. Especially vs a non tuned 7.3 I feel like a tune and it's going to be a super reasonable power level without sacrificing reliability. I got a tuner on the way already.
I'd say whatever truck you look at just bring your Bluetooth obd or AE or something to monitor it while you drive it and steer clear of the rust.
And fwiw mine has about 15k more miles however it's clean inside and out with no rust and it was $4k less then the one your looking at. There's deals to be had, just got to be on the hunt.