I was one of those people from 6GC.net that built a good running 5S-FTE back in the mid-2000's. Some of us did use 315cc injectors at first but they really weren't large enough and we all outgrew them pretty quickly. I believe I used red, high impedance RX-7 injectors, although I can't really remember what size they were now. You definitely need some form of knock monitoring. Our engines were all 94+. (My specific engine was a low mileage 1999 5S-FE so knock sensor and MHG standard)
I'm not here to dissuade you from your project, but it is worth mentioning that
every single one of us eventually swapped to 3S-GTE.
edit: 460cc injectors High Impedence
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