I've got 4.10 gears in my Firebird and at 70 mph it turns about 2000-2100 rpm on the freeway. Also, the 200-4r can be built to handle 1000 horsepower if so desired: http://www.cpttransmission.com/ .
X2... I have a 2004R stage 2 built to handle up to 750HP/650TQ by Lonnie Diers at Extreme automatics. He is quite knowledgeable about them and he is also a racer.