HP & Torque numbers for Cross Ram

[ERA 626]

I am getting mixed statement from different builders.
I am having Morrison make me a cross ram stack Fuel injection setup. I have a local builder friend (extremely old school) who has offered to build my motor. He has recommended using the megasquirt with a cam sync sensor (no distributor) he has done one of these on a SBF and runs great on the run stand. I am having a cam sync sensor custom made as well, nobody makes one for an FE.

I want to get 600hp/600 torque numbers from a 482 CI shelby Block/heads.
Soon after I jumped into this (ship my block & heads to new zealand) I met Joe. Joe is the engine builder for Shelby engine Co. Very humble nice guy. Joe has built hundreds of FE motors, he knows his motors.

My local guy (wont mention names) lets just say Dave. When I told Dave I wanted these numbers he called me stupid and ignorant. Yet Joe said no problem, but Joe is not a mega squirt guy. I am reading all over the internet these numbers are very doable and very common on a high end FE build. am I being un realistic to expect these numbers and still have an enjoyable fun to drive cobra? I do have extensive race history on a 110mph Shifter Kart, so performance/power is important to me. Advise?