The MPH doesn't really indicate any spinning, so...

Even if it actually is the convertor that's causing the 60' to be a little off, I wouldn't mind giving up a little 60' for a little tighter convertor on the street. But that's just me....

It still ran 10.68 on pump gas and "street" tires, with NO tuning. Let's not forget that. I would make a safe bet that it has more in it.