Well choke, electric or manual?

Do you have a carb number? That may not be the original carb so finding a choke that works correctly may be a tall order. Is the choke cover you pictured correct for the application? I looked through the 66 manual for photos but no help. A manual choke cable may be the way to go. I have never seen any electric chokes or conversions for those 2 barrels. That looks like a BBD 1 1/4" that was used on the 273's. I believe all the 6's in 66 had 1 barrel carbs on them. My guess is a original 66 exhaust manifold with the choke coil cavity a later model 2 barrel intake and a 273 carb.