After posting this question, I called the guy who sold me the car. He actually built this car for a customer who sold it to him after an accident.
I told him about the hard shifting and he told me that this tranmission was rebuilt with heavy duty parts and is a step below a racing transmission. The car was then tuned to achieve maximum performance. He did mention that it shifts at full-line pressure to handle the power and put it down properly.
Unfortunately, he had no specs to provide on the rebuild since it was a while back.