Here's a kit you can install yourself: https://www.700r4l60e.com/store/home.php?cat=58

Dana has the experience to help you mod yours to handle up to 900HP (less without breaking into the case). Give him a call.

We also have a sponsor onsite at Finish Line Transmissions | Performance Transmissions | Torque Converters | Transmission Parts | Transmission Service
I don't know this person but he lurks on this forum often.