I've set vehicles to idle in open loop. Heck, even GM has done it. Closed loop idle is for emissions, to help keep the converter working. But closed loop idle is almost 15:1 AFR while engines usually like to run well between 12 and 13:1 afr. And if you have a cam with reversion causing "extra" MAP pulses or incomplete combustion then you're fighting misleading O2 readings and an ecm that is trying to bias fuel when you may not want it to.

As far as the WB goes, you'll need to locate an unused 0-5V A-D sensor input then ensure the ALDL is displaying the data.