Magnum 300 crate engine - how should it go when tuned up right?

You have 0-60 in the 6 second range. That's right on top of the factory 340 cars. That's about exactly where it should be.

Thanks. That perspective is appreciated.
I took for granted that a car with much wider/better tires should have a big advantage (along with a more efficient transmission)...but since those factors were likely not the biggest impediments to the old 340 cars, they might not make that much difference. Being comparable to a stock 340 car is probably a good sign that the car isn't way out to lunch on performance.