I have a 65 Stang, i picked up the airbox from another member here, i have the drop base as well. I test fitted it w/ and w/o my monte carlo bar and it will not fit w/ the bar in place the alginment is right in the
way. not sure what your application is for, you may have clearance on
a different veh.
If you can't make that fit, you could get a carb hat like the one offered by www.superiorairflow.com. I put one on my pickup, and made an airbox with cone-style K&N filter. Here's a picture, you can check out the pics at my web page.
Mine was the plastic version, which it looks like they don't have listed on their website anymore, but you might still be able to get it if you email them, it wa significantly cheaper than the aluminum version (like 1/3 the price).