OK, so what do he write you up for? Using what speed timing device (I assume its VASCAR - time over distance, unless he was a statie)? There shouldn't be that much of a discrepancy between your speedo and his reading, and since there was you could plead mercy at the judge at say you never intended to go THAT fast.
Go find the markers the cop used as a measured distance (prolly big white lines over the road) and measure it with a tape measure. Then start playing with the math to see how little error would get you below 49 MPH. The cop would not be allowed to pull you over for less than 10 over. I know a guy who beat two tickets doing just that (must have been a nice judge though).
Oh, and PennDOT will be sure to let you know exactly how many points you have once you plead guilty/get found guilty of an infraction.
