2800 rpm @ 60 mph = 9.5% slip. That is not good in my opinion but I don't have experience with highway slip only at the track.
I have had converters slip as much as 13% at the finish line. My current Frank Lupo 9 inch in the race car slips 4% through the traps.
My new build will have a Lupo 9.5 inch converter (its currently in the street car). I will be running 4.56 gear with a 30 inch tire but do have a Gear Vendors OD for it. That drops the 4.56 to a 3.55 gear. It will be interesting to see how it behaves on the highway.
My 69 Dart had less then 3% slip at the finish line, it was a great ATI converter. I like 5% or less, some 8" converters are useless on the street.
You'll love the Gearvendors, hopefully you're converter is tight enough for it. There's a fine line cuz I had a 10" nitrous converter years ago that was a super tight pig without nitrous of course.
