Speedo gears needed

[oldude]

We just finished putting in a 406 sbc, 200r4, 3:42 posi in my sons 83 monte ss. I had him pace me on the highway and when I was @ 55mph his speedo read 70 mph. Which gears do we need to corrct this? Or is there a web site that I can take a look at?
thanks

 

[WE4]

old dude..

I can make up most set ups. what we need is tire size, gear ratio and we can come real real close. Let me know the above items and we will see what we can do. I can probobly do it with used stuff so price is kept to a minimum.

BT

 

[oldude]

tire size is P235/60/R15. Diff is a 3:42.

 

[WE4]

ok easy easy like a gn you need 11 tooth orange gear and a 30 tooth blue driven. Two ways to go about getting them. One is buy the bullet complete but that is pricey. I think I do not have any more used 11's tho. New they are on the site and I have in stock. As for the blue one they are 9-10 dollars and I have them both new and used. Let me know and I can ship out Monday. I need to run but will ck back tonight. Feel free to email or place a parts inquiry off the site or post here.

Bruce