1966 Coupe - Looking for Radio Advice

[MustangB]

I have my stock AM radio in the dash. I have an amp in the trunk that powers my speakers (kick panel and back seat panels, plus a pair of 4.5 inch full range under the dash on the tunnel in a custom enclosure). My trick is that the amp is fed audio signal via a bluetooth receiver which in turn gets music from my iPhone or my iPod classic. Therefore, I have a cordless system that is theft resistant since I remove the "head unit" each time I leave the car.

 

[PoppyMod]

I am about to install a CAS radio in a 67 Mustang. There was a (cheap nonworking) CD player installed in it when I got it. I noticed a Hide-Away Antenna under the dash. I also noticed another antenna wire running to the lower kick panel, it stops on the other side with a odd connection. There does not appear to be a old antenna location on the front fender. What do you recommend as the best antenna option, Hide-Away(where to install) or exterior Vertical Antenna?

Hi, Was this a "radio delete" car, or do you think the PO just didn't want a radio?
I would pursue a hidden antenna. All of my cars (newer) have hidden antennas, so good after market units have to be out there.
Just my thoughts.
Good Luck!