Andy, I don’t know if you got anywhere with this. Maybe I’m on ignore or you discount my experience. Anyway, this situation is totally fixable if you would disclose the ecu brand/ model.
I assure you that the engine can idle much lower by using the correct strategies.
I’ve been tuning engines with these idle characteristics for longer than most people in the industry.
Once you learn how to make a large cam, low compression, odd fire v twin to idle low and even, an 8 cylinder is a piece of cake.
Even if the converter is to tight, you could program a staged dump valve for the converter in whatever conditions you desire.