I have a 1969 with a 302 engine. The car did not come with A/C. There are two heater hoses which need to be properly clamped down/attached. At the moment they are not attached to anything in the engine compartment and basically are sitting on the valve covers. ..............
The two hoses pass through the firewall and attach to the non-AC heater box/heater core at the nipples. No bracket to hold them and clamps only in the interior - not visible from engine compartment on a non AC car
Different year but same design and route
The other ends attach to the nipple on top of the intake (front) and the other to the second water pump nipple at the front of the engine
There is a whole handful of pictures of the engine compartments in the Unrestored 69 Mustang section. In some cases (common after all these years) the hoses and clamps have been replaced but will at least, in those examples, show you where they attach. Any of the non AC small blocks should help
If your going for the original look you'll need tower clamps at both ends. Ford part numbers will do you little good but undated reproductions are available