Wallace says you're making about 45 more horsepower, and it might be more than that, considering the rear gear change.
A converter can be a huge improvement. Think about it this way: how much more horsepower is your engine making at 3500, compared to 2000 rpm? 50? 100?
And I agree with 318willrun, 78 mph is enough for 8s, 60 ft is where the et improvement is at.