Add me to the list of people who ran one of those on a 318. 69 motor with a comp 252 cam, 625 AFB, in a 79 short bed 2wd truck with manual steering and brakes, 833 OD and 3.55 gears in an 8-3/4 from a 60s truck
I couldn't believe how well that thing ran. The way I used that truck at the time I should have had a 1 ton. Towing, hauling with the back bumper about dragging at times, but when empty I drove it like I stole it, in those days. Great mileage when empty or nearly so, plenty of power for what I was doing. Idk how much of how it ran had to do with the intake but I'd try another. As far as the running out of steam at 5200 revs, I can honestly say that I don't think that I ever tried to get much of anything that I have ever owned much over 4000 revs.
So if that was the only limitation, it wouldn't bother me at all.

Back when I had carbureted vehicles I would put a vacuum gauge on to my vehicles quite often, looking for that last little bit that I could get out of them, and it did seem like I had more vacuum on the gauge from that engine than any of the other 318s that I had around then, which were quite a few.