Awesome car. The interior is why you buy anything like that, nothing like it nowdays.
For the engine, I would seek MPG and responsiveness over maximum power.
A lot of Ford engines from that era were designed in the late 60's with compression ratio's pushing ten. On the 460, it was over ten. Then, Ford got into the habit for the next 30 years of detuning those engines to make whatever smog limits or whatever other mechanical limits OK on their vehicles. Like the 5.0 Mustang with a T5 manual, the T5 was rated at 300ft lbs, so the 5.0 was detuned to have less then 300 ft/lbs. They detuned their bigger engines to make smog, but also to make the auto trans last longer, at least that was the theory.
I would do the dual exhaust. But I would choose significant mufflers to keep it silent. Not restrictive, just big and quiet.
The best thing for the engine would be to return it to it's "Thunderjet" origins one way or another with compression. Probably with pistons, I doubt there is much to do with factory heads especially past 1970. If I recall right, 1974 factory big block compression was barely over 8, may have been 7.9. 73 was a bit better, a bit.
Ford engines from the 70's were slime pits inside from oil, carbon. Even at that milage, I bet it is slimed up inside. Nothing to worry about of course, but when you get into it be prepared lol.
I think you are going to love every minute of that ride. Driving a pillow is always a good time, and people will look and give a thumbs up.