Is this the Tube you're referring to or looking for? It's identical to my original old rotted Tube, around 3" long but don't know if it was originally chromed; I'll have to remove the chrome if not. It's confusing as it's nowhere near as long as the repro Tube you find in catalogs, which isn't correct anyway, but what was the correct length for Dearborn 200's...3", 5", both? Granted, my Engine is a '65 but if both years used the same Tube, then this one, I would think, is correct...not 100% sure though.
If it is correct or acceptable for Concours Judging, then you can find it listed in most catalogs as being used on the 68-70 390GT and 428S/CJ at the Water Pump. If it needs to be the longer tube, I wonder if you can use the one listed in the catalogs for your year and simply cut off the 90; it'll end up looking like the one in the 2nd photo. So that the Heater Hose has some bite though, you may have to create a couple of grooves of your own, similar to the original.
Ray
P.S. - where you see the Brass Fitting on the left in the first photo is where the short Nipple goes; Brass Fitting not used for non-A/C cars, short Nipple threads directly into the Cylinder Head.