Yes, the 1500 Roadster sender is the same as the 320 except for the arm being bent different.
I will take some pictures tomorrow of both side-by-side and try to figure out how to post them here. If I can't figure it out I will mail them to you Wayne - since you know how to do it.
My email is in the "truck brothers list".
It seems to me that the very early 1500 Roadster sender could be used no matter which way the arm is pointed as one can just turn the sender till it clears everything inside the tank and screw it in(5 different positions), but how far the float drops and lifts is hard to control, I think getting it near empty would be the most important, full is where ever it is, empty is kinda important.
I believe I have a later 66/67 Roadster sender, as it will bolt right onto the tank, but all the way down(empty) shows as full on the gauge, the arm holding the float looks alright, and it is actually held in position in the sender with a collar, and I was thinking it might be reversible, meaning pull it out of one side and insert it in the other side and tighten down the collar, but this action eliminates the stops . but if the early 1500 unit is available I would suggest just buying one of those if it will fit.
Of course a new wire on a new sending unit(late 1500/1600 if the early ones are not available) maybe could just be bent the other way, but I am always in fear that bending a wire/rod 180 degrees after it was bent 90 degrees will break it, although I don't believe it would have to be bent 180 degrees, it looks closer to 100/110 degrees back, if it really needed to be bent back 180 degrees I would generally try to remove it and twist it instead, then re-install it if I could.