According to the 65 Mustang Electrical Assembly Manual (AM0008 pg21), the 200 CID I-6 heater hoses went thru a strap attached to the RH firewall-fender brace, the strap attached with two screws; the 289 HP was routed under the PCV tube (assembly manual item 17), not attachment to the brace (the other V-8's, 2V and 4V went to the choke and back along the valve cover-intake "dip").
(The 66 installation was the same as 65.)
(The 65 and 66 service manuals show different hose routes at the choke.)
Jim