does 16.5 inches uncompressed sound right?

Sounds pretty close. JBG says that their Superlift leveling coils are 17" unloaded.
http://broncograveyard.com/bronco/i-33500_superlift_coil_springs__1____-2__lift.htm

I'm wondering about these "severe duty" coil springs from NAPA. Would 19.54" Free Height be too much without axle drop down brackets?

http://www.napaonline.com/MasterPages/NOLMaster.aspx?PageId=470&LineCode=NCP&PartNumber=2775390&Description=Coil+Spring+-+H%2fD+-+Front

I'm wondering about these "severe duty" coil springs from NAPA. Would 19.54" Free Height be too much without axle drop down brackets?

http://www.napaonline.com/MasterPages/NOLMaster.aspx?PageId=470&LineCode=NCP&PartNumber=2775390&Description=Coil+Spring+-+H%2fD+-+Front

I would have to think yes. Most people feel the leveling coils are too much. And there are very few of us that didnt have to crank the camber all the way out.

does 16.5 inches uncompressed sound right?

I would say yes. I just measured my old dual rate leveling coils and they measured 16'' uncompressed (uninstalled). They have been used for about 14 years so they have probley lost a half inch or so.