This is good advice from cr-rex. In my opinion, I wouldn't swap injectors unless the car already had a wideband O2 sensor and fuel pressure sensor installed, and you have datalogs showing how it behaves during idle and cruise and full throttle. Without that info you are flying blind, and won't have enough data to compare against if (or when) the car doesn't run well after swapping injectors.

Also, FYI using the Power-FC is making this even more difficult than it should be. I haven't used a Power-FC myself but I've followed their tuning groups long enough to gather that idling with bigger injectors is unnecessarily difficult to tune compared to modern ECUs. On better standalones you will probably need to make some simple fuel map adjustments after swapping to larger injectors (aside from telling the ECU the injectors are different), but with Power-FC it sounds like you need to do weird stuff like negative lag and maybe even tricking the ECU into not using the default idle maps.

Also, you've probably flooded the engine from running too rich or too much cranking fuel. Search for RX7 un-flood procedure, with luck you can just crank without any fuel going and clear the engine out. With less luck you might need to remove spark plugs, add oil or ATF into the combustion chamber, or even turn the engine by hand to see the apex seals and un-stick them by poking something in there. Good luck.