If you can't find a hose that fits then make the radiator fit the hose. That is what I did. I used a C body radiator and had a shop move the lower outlet over a few inches so a standard hose would fit perfectly.
Nicely done! I will keep it in mind for a back up plan. If you don't mind me asking what fan and spacer are you using in the top photo and how much clearance did you have from the water pump to radiator?