spedo gear/start problems, 1987 Mustang

I got a ticket the other day and I am going to try and beat it in the court. It wasn't reckless thank god but really darn close... 80 in a 65. Anyways I was going to change the speedometer gear to throw it off a little then get it calibrated. I have stock '87 5.0 manual gearing and a 140 speedometer. What size gear should I change to so that I can throw it off about 10 mph?

Also I went the start the car the other day and when I tried to turn the key and crank it the key binded up and wouldn't turn far enough. I can turn it enough to get the power on and fuel pump but I cant crank it. It feels like there is something binding up so that it cant move. I got around it by popping the hood and taking the plug shaped wire off little module on the fire wall (not sure what it is called) and connected that with power to get it to crank. So what is broken and how do I fix it?