I know you mentioned Wet Okole. I have them on my Bronco and love them. I have 1988 Nissan Pulsar NX seats in mine and they made them fit perfect. I checked their website and it looks like they make them for OEM 66-77 Bronco seats if I am not mistaken. Don't let the generic seat diagram on their seat builder site fool you, its just a generic bucket seat diagram but comes fitted perfectly. You could always give them a call/email to make sure. I like how you can add map pockets and such to them.
FWIW, I never have a top or door on and have been caught in the rain many times and they work great.