Try Mackay rubber. They have a tech enquiry email/form, and the bloke on it is really really helpful. I was trying to find a hose for an A/C 70 small block and he took pictures, got ones from the warehouse and compared, did a cross reference to the Ford part number.
All of it done fast, friendly and informative. And he appreciated learning about Mustangs too. I did warn him he'd get more calls.