I thought this might be helpful to some people so I thought I would post what I did with my speedometer. I found out that the Speedo head out of 67-72 Chevy trucks are identical to the ones in the 47-53. Only difference is the gearing since they are 100 mph gauges. I took the head out of a 67-72 cluster I had laying around and put it in the 50' bucket. I then simply made a sticker with the right scaling and numbers and the design I liked and printed and applied it to the 50' face. Now I have a factory looking Speedo that goes to a hundred and has a good odometer for very little money!...I have a more in depth write on my new blog and the graphic is available for whoever wants it there.
https://mayberrycustoms.wordpress.com
Check it out!