So, a couple things.
First, your test result is 8+, so you currently don’t know if your result is 8, or something higher than 8.
You are correct that Ph is indeed a factor on ammonia toxicity, but 8+ppm total ammonia is still too high.
See the attached chart for a handy reference for ammonia toxicity vs PH. At a ph of 7, a 10ppm total ammonia result is harmful with long term exposure (it’s not immediately toxic, but its getting close).
But...if for some reason your Ph bumps up to 8, your fish will die immediately.
If you can get your test result to 2ppm, and can guarantee that your Ph stays at 7, then the ammonia would be harmless, even long term throughout your cycling process.
However, if your tank has been running since at least March, you should have a fully cycled tank already and shouldn’t have any ammonia at all. Did you keep your sponge in your filter when you added the bio rings, or did you throw it away?