It seems to me that Post #8 of that thread explains the difficulty to achieve proper iddle without two adjusting screws for RC use, and the reasons.

For some time I was working repairing and servicing weedeaters and dealing with these little engines.
Many times, they needed a spray shot of carburator cleaner or WD-40 to start.

Yours is an interesting project, please don't throw this engine in the garbage!!
Regards!