Mike i'm not sure how big of holes you drilled but i was thinking... (dangerous i know) lol
My Joe Gold has( 4 ) 3/4 inch holes for the vents... 2 on each side. Most of the time i have one side completely closed and the other only partially open.
Chickens i go full open and then end up dialing back to just one sides vents. It just doesn't take much oxygen to keep good temps in this thing and if you change the nipple side to a valve you could get pretty good control.
You shouldn't have to use the bottom vents much at all...just to get it really hot like for chickens but end up up closing it off also.
Just a thought anyway. It's apples and oranges with the silver and gold.