The engine you have now is about the limit of what you can do in terms of street power with a production block, hyd roller cam and production style heads. The issue is that you need to have the engine "on the cam" at 1800 rpm if you want to cruise down the freeway in overdrive. So if you're going to be "on the cam" at 1800 rpm then you can't have a camshaft with a powerband of 4000 to 7500 rpm.

The new engine that your are talking about won't work with a 5 speed OD transmission. The bigger ports, bigger intake, Dominator carb and bigger carb will not work at 1800 rpm in OD on the freeway. The air velocity will be low, torque will be low, and gas mileage will be horrible. That engine will work great starting at 4000 rpm and will make 700 hp at 7000 rpm, but it won't work pull a heavy B body down the freeway in overdrive at 1800 rpm.

If you want a 700 hp race engine then put a built 727 behind it with a high stall converter. If you pick the right converter you can drive it on the street and it will be a very fun ride. It won't be great for cruising on the freeway but that is just the way it is.

If you want 700 hp peak power and OD transmission then buy a Hellcat. That is what those engines are designed to do.