If the radiator and grill is out of the car, you can look through that opening and see how much room you have to work with. If you get lucky, the air cleaner might clear the under hood reinforcements which will gain you some clearance.
Use the deepest drop base that you can get away with. An Edelbrock carb with electric choke is limited to a 3/4" drop base. You can get a 1" drop to work with a little surgery to the base. You'll probably be able to go deeper with a Holley carb. Once you have the base figured out, you can adjust the lid height with the air filter thickness. Get the lid as close to the hood as possible while leaving a little room for engine movement.
Maximizing your drop base AND getting the lid as close to the hood as possible will let you run the tallest filter. Thin filters look goofy.
Don't forget about the carb stud/wing nut height. For my project, I'm going to make a custom hold down fastener that is actually lower then the top of the lid. This will let me get even closer to the hood and maximize the air filter height.
