I've driven the factory cars and they ran just fine, even with the stock 3.50:1 gearing. I think stuffing one in your '79 is a great idea; 4.30s are the right gear for a 26" tire, according to Ford.
You don't have to ask "should I build a high rpm motor"? Because the moment you decide to bolt the 4V heads on the 302 you've already set that in motion. Its unavoidable, it shall be a high rpm motor.
So don't fight it, and don't try to make it somethng it isn't.
Basically the Boss 302 does everything 800 rpm higher than a 351C 4V. But the same Cleveland principles apply. Everything is 180 degrees backwards from motors with small ports and small valves. The Cleveland heads build the high rpm power, and the cam and intake manifold build the low rpm power. So spec a cam with relatively short intake duration and limited overlap, and use a dual plane intake manifold with a full height (un-cut) plenum divider. Carb & ignition calibration are also critical to running smoothly on the bottom end. Your 4V heads have either 63cc chambers or 66cc chambers, whereas the Boss 302 heads had 58cc chambers, so you'll have to make up that difference in volume somehow.
I think you'll like the motor, my advice is go for it.
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