The 65's never came with a 350P engine.
It was either a 326 or a 389 depending on the model and options.
The 350P did not make the scene until 1968.
That's why the guy cant find a 350 optioned 65 in his data base.
I believe the 65's did not use a cross flow radiator either.
Whats the problem is the water neck(thermostat housing) angling the wrong way for a 1965 hose to work right?
If that is the case a 1965 style water neck,if there is such an animal, would solve it if you are still running a stock type radiator.
You may have to look through the Gates master catalog yourself and find a hose with the dimensions you require.