Chrisascmclaren

I have an 87 instrument cluster with the 85mph speedo that is weathered. I found one out of an 89 with the 140 speedo. Everything works with no problems. Only thing is that my car only has 52000 miles on it and this one reads 77000. I want to keep my original miles of course. I can roll it forward with no problem except it will take forever to get to my mileage. Is there a way that I can roll it back or whatever faster to get my miles to be correct???