The 741 case will be fine. Everybody always freaks out when they see that it was intended for "low weight/low horsepower" stuff. I've beat the crap out of one in a '70 Charger 440/727 and never had any problems in 20+ years. I wouldn't hesitate the slightest to put a 741 case in a 500+ horse street car. Good luck trying to break it.