Mito, Wow! I've often thought of the same- too many other things going on with me. I wish you great success and look forward to seeing your results.
I will offer these observations for you to consider before a final design:
Colour- Both red/orange and green seem too dark in rendering- may need adjust with printing.
Serif on numerals "1" appears to not be on originals.
In photos below- note placement (s) of Speedo part number and the specific white "6T" for use on the Triumph Thunderbird....was the revulator markings used on any other make or model?
A nice thing is that this will be very close to accurate with a Smiths magnetic 1600!
Please note- I offer this as information to help you achieve your best design- I absolutely love that you are doing this!! All my best! Joe
1st photo- old non working unit filling the hole on Miss Penny. Note she has got ten+ years with this Speedo filling the hole- minimal sun damage!
2nd photo. Supposed NOS unit currently on EBay.