I highly recomend the 4x10 from turnswitch.com .
It is available with a small magnet,like original, so there is no issue with clearance, and it's 8 ohm so it will not burn up your original radio like the 4 ohm replacement speakers will.

Greg

Wards Classic Car Radio Repair Specializing in restoration and sales of Mopar A B E body radios
We can restore YOUR radio usually in less than 14 days
Visit our NEW website..
http://www.wardsclassiccarradiorepair.com
gregward@mchsi.com
phone 256-852-0955