I'm a bit confused with what you say.
If you really drive at 65, the sat nav should read 65 and the speedo between 67 and 70.
However, i would not rely on the sat nav only. They are not always accurate.
In order to calibrate my speedo i used three sources:
1. I went for a ride with the 'speedo test trick' (yes, the test mode) and i compared with the digital value which should be accurate.
2. I used the sat nav
3. I used one of those funny speed notifications on the street. (the ones that show you how fast you're going)
My speedo would always show a couple of MPH more than those. So far i have not received a ticket, so i consider them to be accurate enough!
Keep in mind tho, that this was my case where everything was working fine and i've got the car since new. What worries me, is the damage you mentioned that your car had in the past. Could your problem originate from a different source, such as a faulty sensor or incorrect repair? The images you mention might help.
If i were you, i would start by going to a mechanic to confirm it is only an issue with the needle and if the cost was unreasonable, i would attempt it myself.