A lot of that is going to depend on what transaxle you decide to run with too.
There are several options that would allow you to push well beyond the 500 HP envelope. I would be happy to discuss what they are with you if you would like.
Feel free to give me a call, I am always around to help.
Warmest Regards,
Erik Johnson
Carquip Sales
(303) 443-1343 ext 2 work
(720) 980-9407 cell