Picture of 340/360 head porting....Mistakes?
Things I notice.
You take awesome notes. Can't emphasize that enough.
Read the thread on speedtalk I told you about. They discuss laying back the chamber. I suspect most of what you found when you filled in th chamber was where you stood up the wall on the backside of the intake.
Top cut, top cut, top cut. That has as much to do with exit loss as almost anything else. That and the angle of the seat.
Also, I agree with screws and Brian on the floor.
Keep testing. Never stop taking notes so you never have to rely on memory. Since you can't go up in test pressure go down. And flow the ports backwards. I suspect what you will find is that everything you gained in filling in the quench part of the chamber, you will gain in reverse flow. That is bad.
Exit loss, exit loss, exit loss.
Reversion, reversion, reversion.
The two go together like peanut butter and jelly.
Nice, authentic, documented work.