And damn those Rad Rides guys never cease to kick the bar 3 notches higher
You could make an F1 setup like that work at lower pressure, but the 700psi is all to help atomization, cooling, charge consistency etc. From what I have read (racecar engineering) it is very effective but not even remotely needed for a street vehicle.
The biggest issue I see with having the injectors outside the runners like that is low rpm performance would be marginal at best. You would need a super strong airflow signal just to suck the fuel into the chamber at a somewhat consistant rate.
If you're just trying to hide the rails/injectors there are quite a few ways (depending on the manifold style) that would be substantially easier. On a single plane you could put the injectors under the runners, use thread in injectors with stainless lines, and a large fuel block at the back of the manifold. The packaging would take a ton of time but it would be super clean.
being a little crazy myself i'd like to use a composite kinsler, single t/b, and lay the injectors down under it so they shoot about as directly into the ports as possible. Like this: but with the revised injector locations.