I agree with Davis you have a miss in that combo, a worthy is a light car and that big motor should easily be a 4.6-7 car even with conv. heads. Shot us some more info on the combo.
The egt should be around 1150-1200 in the 1/4. I have noticed when using 2 different egt gauges/probes that it may be atleast a 100 different from the other. Just need to get close and tune from there.