I have asked one of the companies I've reached out to for a quote for 318. I'm betting they would have to be individual numbers since there's no good way to connect 3-1-8 like there is 340 in the photo above.
True that. Something I didn't think about. It would be ok to connect the numbers ile in post #6 and 13 above. The 340 in my photo has a small bar in between the numbers. It is black like the side of the numbers and not noticable.